// analysis
Why your budget tells a different inflation story
French inflation, groceries and housing: official data and a local calculator explain how household spending changes exposure to rising prices.
Sources and reading context
Topics
Contents8 sections
Price rises reach households through very different budgets. Housing costs, necessary journeys and shopping habits shape each household’s exposure. Understanding the pressure on a budget means looking at the level of prices, the composition of spending and the money left available.
On 30 October 2026, France’s statistical office, Insee, provisionally estimated that consumer prices had risen by 3.4% over the year to October, following a final reading of 3.1% in September. The first figure, a year-on-year rate, compares October with October; the second compares September with September. Final October results are scheduled for 13 November. This sequence of dates may sound administrative, yet it defines precisely the question that each rate answers. R02 R03
At the checkout, the comparison often reaches further back. We remember a price from before the sharp increases, the cost of filling the car, or how much of the budget food used to take. Insee documents that shift in price levels: between the 2015 average and the first half of 2026, food prices rose by approximately 35%, compared with 23% for consumer prices overall. These cumulative changes cover a different period from today’s headline figure. R01
The gap between a national index and everyday experience deserves a closer look. A family buying more food, someone who needs a car for work, a tenant and a homeowner who has paid off their mortgage face different constraints. Their circumstances also depend on the products they choose, the support they receive and their income. A household label captures only part of that picture.
Making sense of the difference begins with separating these questions: which prices changed, how much of the budget was exposed to them, and what resources were available to meet the resulting bill?
Past rises stay in the total
Inflation measures a change in prices between two dates. The price level carries the accumulated effect of successive changes. This simple distinction is essential when reading a budget. The European Central Bank also uses it to explain differences between measured and perceived inflation. R12
Consider a constructed example. A €100 basket rises in price by 10%, taking its cost to €110. The following year, the increase slows to 2%. The basket now costs €112.20. The pace has eased while the bill has continued to grow. The increases compound: multiplying 1.10 by 1.02 gives 1.122, equivalent to a cumulative rise of 12.2%.
This helps explain why an improvement in the annual inflation rate can leave a budget under pressure. The same arithmetic works in the other direction: a price reduction reverses part of earlier increases, according to its size and the price to which it applies. The starting level always matters.
Method and scope
Insee series 011813717 (food) and 011814630 (all items), statistical base 2025, France, all households, not seasonally adjusted, version collected on 30 October 2026. Each monthly index is divided by the mean of the twelve 2015 observations, then multiplied by 100. Lines run from January 2015 to June 2026; the panels compare the 2015 average with the first six months of 2026, rather than June alone. Calculated levels: 134.6796 and 122.5250. The vertical axis explicitly spans 95–140. Long series are backcast under Insee’s documented method; the averages agree with the rounded 35% and 23% increases in the 15 October publication.
The figure follows the monthly indices for food and consumer prices overall. We have put both on the same reference scale, with the 2015 average equal to 100. Their averages for the first half of 2026 then reach approximately 134.7 for food and 122.5 overall. This calculation reproduces the rounded changes in Insee’s publication and, more usefully, shows when the gap widened. R01 R04
Remembering an older price therefore provides information about a longer period. Frequent purchases can also make particular changes more noticeable. The ECB describes this mechanism for everyday shopping. It offers one possible explanation for perceptions; assessing the constraints of income and expenditure also requires looking at the actual amounts involved. R12
Each euro gives a price its weight
The consumer price index, or CPI, tracks prices for products with comparable characteristics. Each product contributes to the result in proportion to the expenditure it represents. This weighting gives more influence to categories accounting for a larger share of national consumption. It describes a collective pattern of spending, updated annually. R05
A household has its own allocation. Suppose a category represents 10% of its starting basket and prices in that category rise by 20%. In a simple calculation with fixed weights, it contributes 2 percentage points to the basket’s increase. With a weight of 25%, the same price change contributes 5 points. Exposure changes with the share of spending devoted to that category.
The example keeps the two ingredients separate. The category’s price increase stays the same; its importance in the budget changes. Reading both together explains how a common movement in prices can produce different overall results.
The 2026 data provide a revealing example. Over the common window from December 2025 to September 2026, the energy index rises by approximately 22.17%, the food index by 1.43% and the services index by 2.26%. These are nine-month changes, using final data available on 30 October. Our calculation uses five broad categories: food, tobacco, manufactured goods, energy and services. R03 R04
Method and scope
December 2025 to September 2026, definitive base-2025 indices and national 2026 weights. l0g calculation: contribution = weight/10,000 × (September index/December index − 1) ×100, in percentage points. The five contributions total 3.1217607% before rounding. The published all-items index gives 3.1215608% over the same period; rounding and aggregation explain this very small difference. Contributions are displayed to three decimals, the energy formula and total to two. Chart segments start at zero; manufactured goods contribute slightly negatively. This teaching calculation is neither an official contribution series nor an annual rate.
In the national weighting structure for 2026, energy accounts for 7.64% of the basket. Over this window, it contributes approximately 1.69 percentage points to the calculated increase, out of a total close to 3.12%. This illustrates how a relatively small category can make a substantial contribution when its prices move sharply. The contributions shown are our calculations from the published indices and weights. R04
These calculations require a consistent calendar. The CPI is linked annually: its weights evolve, and successive annual segments are joined together. Insee’s simulator and Eurostat’s documentation explain the procedure. Simply averaging index levels across ten years would leave out that linking process. Our tool uses a single window within 2026 to make the effect of weighting easy to follow. R06 R11
Since January 2026, the CPI has used a 2025 base and an updated detailed classification. Insee has reconstructed the historical series used here on that basis. The number assigned to the base year provides a calculation reference; comparisons depend on ratios between observations within the same series. The documentation explains the changes in classification and how series are linked. R05 R15
Housing commits income before you shop
Housing expenditure helps explain why national weights can differ from an individual household’s experience. Rent absorbs a substantial share of some tenants’ resources. Its CPI weight is spread across the consumption of all households, including those paying no rent. Home purchases and housing-loan repayments fall outside the consumption expenditure tracked by the index. R14
Insee also measures housing through an indicator designed to describe its budget burden: the housing expenditure-to-income ratio, known in French as the taux d’effort. It relates expenditure on the main home to income. For the net ratio, housing benefits are deducted from expenditure. A study published on 23 September 2026 describes circumstances observed in early 2024. It provides a structural reference from a period preceding the latest price increases. R07
Method and scope
Insee Première No.2128, published 23 September 2026, Figure 1, 2023–2024 Housing Survey. Net housing-cost ratio = total main-home expenses less housing benefits, divided by total incomes, ×100. These are ratios of group sums, rather than means of individual ratios. Income is measured before direct taxes and excludes housing benefits. Expenses include principal and interest repayments for mortgaged owners, property tax, service charges, water and energy. Coverage: main homes in France excluding Mayotte, households in ordinary dwellings, excluding student reference persons and negative household incomes. The axis spans 0–100; bars show a share of the statistical denominator, whose remainder still includes taxes and other uses. This housing measure differs from CPI consumption coverage.
In that study, the net ratio reaches 25.4% for private tenants, 24.0% for social tenants and 23.3% for homeowners still repaying a loan used to acquire their home. It is 7.4% for homeowners with no such loan outstanding. These ratios compare the sum of expenditure with the sum of income within each group. Expenditure includes the principal repaid by mortgage borrowers; income is measured before direct taxes and excludes housing benefits. R07
Those definitions are essential to interpreting the figure. The bar for a group cannot reconstruct a particular tenant’s budget. It does help explain why housing leaves households with different amounts of room to adjust their spending, before any comparison of grocery price increases begins.
Pre-committed expenditure provides another perspective. It covers spending tied to contracts that are difficult to renegotiate in the short term: housing and associated charges, certain subscriptions, insurance and financial services, according to the statistical definition. The term describes the contractual commitment. Food can remain essential while falling outside this category. R13
Someone who depends on a car faces a different constraint again. Fuel spending can vary with the journeys made; the scope for reducing those journeys depends on the workplace, working hours and available alternatives. Here, we treat that relationship as something to examine within a budget, without assigning a supposedly common spending share to all rural households.
A smaller bill can hide a different purchase
Expenditure depends on price, quantity and the product selected. Buying less or switching products can contain the amount paid while comparable prices continue to rise.
Here is a second constructed example. Product A rises from €1 to €1.40; product B rises from €2 to €2.50. Their respective price increases are 40% and 25%. Someone who previously bought one unit of B for €2 and then switches to one unit of A for €1.40 sees the bill fall by 30%. The purchase has changed. Measuring prices requires following A and B separately through time.
Method and scope
All values are chosen for explanation, with no observed product or household. Item A: €1 then €1.40, a 40% increase. Item B: €2 then €2.50, a 25% increase. Chosen purchase: one unit of B at the first date and one unit of A at the second; expenditure change = 1.40/2 −1 = −30%. The products differ; no equivalence of quality or utility is assumed. The diagram explains the distinction between comparable prices and observed expenditure, informed by methodological source R10.
The price tier chosen can also affect the inflation a shopper encounters. An exploratory Insee study published in March 2026 finds that, between January 2022 and December 2025, the cumulative price rise for its entry-level basket exceeded that for the overall basket studied by 10 percentage points. Its coverage is specific: food excluding fresh products in metropolitan France’s hypermarkets and supermarkets, excluding hard-discount chains. Products absent at either end of the period are removed, and baskets are reconstituted annually. R08
This finding encourages a closer look inside a broad category such as “food”. Two people allocating the same budget share to food may buy different products through different retail channels. Our five-category tool keeps the average price movement within each category. Readers need to be able to see that level of detail, and what it leaves unresolved.
Comparing quality is part of the same task. When a pack becomes smaller and that characteristic is observed, the CPI methodology adjusts the price comparison. Product replacements also require adjustments to bring comparable characteristics into line. Deterioration that is harder to observe leaves greater uncertainty. Insee’s methodological article explains these choices and their limits. R10
For a household, a statistical quality adjustment and a cash payment address distinct concerns. A more capable appliance may represent a measurable improvement while requiring a sum that is difficult to finance. That difference belongs in any discussion connecting a price indicator with a household budget.
Three baskets, one time window
To make these relationships tangible, we constructed three starting baskets of €2,000, valued at December 2025 conditions. The amount is chosen for illustration. The first uses the proportions of the national 2026 weights; the other two allocate 20% to energy and 30% to food respectively. The tool shows every allocation. These are examples with deliberately chosen compositions.
The national allocation serves as a reference structure against which the two chosen compositions can be compared. All three calculations begin with the same sum and follow the same calendar, leaving the allocation of that sum as the distinction to examine.
The calculation multiplies each starting amount by the ratio between its September 2026 index and its December 2025 index, then adds the resulting costs. Every euro in the basket therefore follows its category’s index. Monetary results are rounded to the nearest cent within each category before being added together. R04 R06
Method and scope
Constructed five-group model using the assumptions below. Initial food/tobacco/manufactured/energy/services amounts: 2026 benchmark = €297/33.60/477.60/152.80/1,039; energy at 20% = €300/0/400/400/900; food at 30% = €600/0/400/160/840. Each comparative category cost equals its starting amount times the September/December index ratio, rounded to cents before summing. Total costs: €2,062.44, €2,113.10 and €2,062.85. Composition bars each total 100%; additional-cost bars share a €0–120 scale. National proportions provide a conventional benchmark; the other allocations are fictional, with no observed demographic profile represented. Nine months, with no annualisation, forecast or precise individual inflation measurement. The five-aggregate calculation and rounding can produce small differences from the published CPI.
l0g / PRICES AND HOUSEHOLD BUDGETS / LOCAL CALCULATOR
Compare five-category baskets
Constructed starting basket: €2,000 at December 2025 conditions, using national 2026 weights as a conventional composition. Applying definitive September 2026 indices gives €2,062.44. Change the starting amounts to explore the weighting mechanism.
Change the five starting amounts
- Starting basket
- Comparative cost
- Cost difference
- Calculated change
A comparison of unchanged quantities and broad national categories; it is not an official individual inflation rate.
Category breakdown
Food
- Starting share
- Comparative cost
- Contribution to the change
Tobacco
- Starting share
- Comparative cost
- Contribution to the change
Manufactured goods
- Starting share
- Comparative cost
- Contribution to the change
Energy
- Starting share
- Comparative cost
- Contribution to the change
Services
- Starting share
- Comparative cost
- Contribution to the change
Calculation and scope
Each starting amount is multiplied by its category’s September 2026 index divided by its December 2025 index. Every category cost is rounded to the nearest cent, half up, before summation. Shares and percentage-point contributions use those rounded costs. Independently rounded percentages can differ slightly when added.
These are fictional five-category baskets. Each category retains its national internal composition. Energy combines heating and fuels; services combine rent with other services. Savings, property purchases, loan repayments and direct taxes remain outside this consumption basket. It does not estimate income or purchasing power.
All calculations run in this page. Inputs remain in memory while it is open.
The basket using national proportions reaches €2,062.44, an increase of approximately 3.12%. The basket allocating 20% to energy rises to €2,113.10, or 5.66%. The example with 30% devoted to food reaches €2,062.85, or 3.14%. That final result is revealing: a large food share, within this particular allocation and over these nine months, produces an increase close to the first basket’s.
Each percentage describes the change in that constructed basket from December to September. Keeping those dates beside the result preserves its meaning when it is compared with a headline year-on-year inflation rate.
The comparison puts the calendar back at the centre of the analysis. Food prices rose substantially over the decade; within the recent window chosen here, energy’s movement does more to explain the differences between our scenarios. Cumulative changes since 2015 and changes since December 2025 describe two compatible stories. R01 R04
Readers can change the starting amounts. The calculation displays spending shares, comparative costs and each category’s contribution, allowing them to explore how weighting works. Its results remain sensitive to the grouping of products: gas heating and motor fuel both follow the energy aggregate in this exercise, while rent shares the services aggregate with other expenditure.
Amounts entered should follow the chosen scope. Savings, property purchases, loan repayments and direct taxes fall outside this consumption basket. The data are included in the file, and calculations run locally using inputs within defined limits. Each result relates only to the period displayed.
Purchasing power has an income side
A budget’s constraints depend on its resources as well as prices. Higher income can absorb part of an increase in spending; lost income can put a budget under pressure even when prices stay unchanged. Analysing purchasing power therefore requires an income measure consistent with the expenditure and price index used for comparison. National accounts use their own consumption deflator for this calculation. R01 R09
Healthcare illustrates another boundary. The CPI tracks medicines and outpatient care before public reimbursement. The European harmonised index of consumer prices, or HICP, accounts for those reimbursements under its conventions. A change in reimbursement can therefore alter the amount borne by a patient without an equivalent rise in the price observed by the CPI. Housing benefits and France’s energy voucher have a further distinction: they are not deducted in the HICP. R09
These differences in scope explain why a bank statement requires a complementary reading. To trace the source of pressure, it helps to examine comparable prices, quantities purchased, products selected, commitments and income separately. Each change has its own route through to the money left available.
The national index remains useful for following an economy-wide price trend through an explicit methodology. An individual budget supplies the detail of exposure and the possibilities for adjustment. In this investigation, the accumulated food-price gap, the recent energy shock and housing commitments each explain part of the pressure. Bringing them together makes the bill easier to understand and supports more precise questions about the relationship between a published rate and everyday experience.
Method. Research cutoff: 30 October 2026, Paris time. Price data come from Insee’s 2025-base series in the versions available on that date. Periods, geographical coverage and provisional or final status are identified throughout the text and figures. The basket and product-switching examples are constructed. The investigation uses published evidence, with no bank statements, original interviews or observed individual profiles. The references below document the sources and their limits; the calculator sets out the scope of the examples.
Further reading
The ECB survey on households facing bigger bills examines the gap between expected spending and income. France’s proposed 2027 budget traces the income and consumption channels of fiscal measures. These approaches complement price measurement, with their own periods and methods.
Sources and references
Sources consulted on 30 October 2026. Provisional releases, final series and constructed examples retain their own periods and scope.
- Pouvoir d’achat, inégalités de revenu et pauvreté : Quelques questions
Establishes approximately 35% higher food prices and 23% higher overall prices since 2015.
Passages and scope
Price comparisons between the 2015 average and the first half of 2026; other sections use their own periods.
Section 4 on perceived price increases; comparisons for food and all items.
These are rounded figures. Its 3.0% September figure is the preliminary estimate; R03 provides the final 3.1% result.
- En octobre 2026, les prix à la consommation augmenteraient de 3,4 % sur un an : Informations Rapides 266
Provides the current estimate: CPI 3.4% year on year, 0.4% month on month; HICP 3.8% year on year.
Passages and scope
October 2026 against October 2025 and September 2026; published on 30 October at 08:45 Paris time.
Opening text, consumer price changes table and next-release calendar.
A preliminary estimate. Final October results are scheduled for 13 November 2026 at 08:45 Paris time; the calculator uses September.
- En septembre 2026, les prix à la consommation augmentent de 3,1 % sur un an : Informations Rapides 247
Checks the six September index levels, 2026 weights and final 3.1% annual rate.
Passages and scope
September 2026; changes against August 2026 and September 2025.
Detailed final price-index table, all households and five broad groups; revisions section.
Year-on-year changes use a different period from the calculator’s December 2025–September 2026 window. Subgroups must not be added again to their parent totals.
- Indices des prix à la consommation : Base 2025, famille 129209311 (IPC-2025)
Supplies indices, metadata and weights for the calculator ratios and original figures.
Passages and scope
Archive dated 30 October 2026; selected monthly indices from January 2015 to September 2026; calculator December 2025–September 2026; 2026 weights.
Monthly values, annual values and characteristics CSVs; six index identifiers and six weight identifiers listed in the French locator.
French CPI, all households, unadjusted, base 2025. Historical series are backcast and annually chained; source codes and vintage are retained. The categories remain broad.
- Indice des prix à la consommation (base 100 = 2025) : La méthode en bref
Defines metropolitan France plus five overseas departments/regions, CPI/HICP scope, weights and annual chaining.
Passages and scope
Method for base 2025, updated in February 2026.
Page 1, scope; calculation method and production/publication sections.
Describes statistical production; an individual household’s purchases and income require additional information.
- Simulateur d’inflation personnalisée
Cross-checks the unchain–aggregate–rechain method and explains the limitations of a personalised basket.
Passages and scope
Version consulted on 30 October 2026; thirteen eCOICOPv2 divisions.
Documentation; calculation method and limits; calculating a personalised index.
The average spending column refers to monthly spending per inhabitant within CPI coverage. Constant weights and aggregation can produce a difference from the official index.
- Le logement pèse moins sur le budget des ménages en 2024 qu’il y a dix ans, sauf pour les plus modestes : Insee Première 2128
Documents net housing-cost ratios: 25.4% private renters, 24.0% social renters, 23.3% mortgaged owners and 7.4% outright owners.
Passages and scope
Early 2024; 2023–2024 Housing Survey collected from September 2023 to July 2024; comparison with 2014.
Figure 1 and sources/definitions; spreadsheet Figure 1, cells K7/K5/K11/K9.
Ratios of group expenditure totals to group income totals; France excluding Mayotte with survey exclusions. Income is before direct taxes and excludes housing benefits; mortgage principal is included in owners’ expenditure.
- Durant la période inflationniste, les comportements de descente en gamme ont contribué pour deux points à la baisse de la consommation alimentaire, et les prix des produits d’entrée de gamme ont augmenté sensiblement plus vite que les autres
Shows that price changes can differ within a broad food category.
Passages and scope
January 2022–December 2025 for price-tier indices; separate volume calculations cover 2021–2024.
Printed pages 73–74, Figure 7; methodological Box 4, page 78 (PDF pages 8–9 and 13).
Excludes fresh food; metropolitan French supermarkets and hypermarkets, excluding hard-discount chains; products present at both endpoints. Tier is proxied by unit price; this is exploratory research.
- Pourquoi l’Insee calcule deux indices des prix à la consommation ?
Explains gross/net prices, public health reimbursements, benefits and choosing an index for a particular question.
Passages and scope
Conventions and uses described on 15 October 2026.
Sections on CPI/HICP history, HICP advantages and drawbacks, and choosing an index.
Written by index producers; claims about suitability depend on the use case. Third-party illustrations are not redistributed.
- Shrinkflation, « effet qualité », évolution de l’offre de produits : comment l’Insee mesure-t-il le juste prix ?
Describes pack-size and quality adjustments, replacement products and limits to what can be observed.
Passages and scope
Methodological explanation published on 15 December 2023.
Introduction; product-replacement discussion; scanner-data and tariff sections.
Operational counts from 2023 do not necessarily describe 2026. Adobe Stock photographs are credited; original pages and images are excluded from the package.
- Methodology : Harmonised Indices of Consumer Prices (HICP)
Cross-checks unchaining by the previous December, weighted averaging and rechaining.
Passages and scope
Current page consulted on 30 October 2026; no specific page publication date established.
Aggregation procedure / Procedure for the aggregation of indices.
HICP documentation; CPI and HICP coverage and weights remain distinct.
- What is inflation?
Explains expenditure weights, frequent purchases, memory horizons and quality changes.
Passages and scope
Page consulted on 30 October 2026; no specific publication date established for the text.
Different people buy different things; Perceived inflation; Price changes versus quality changes.
These general mechanisms do not quantify their contribution to every French household’s experience.
- Dépenses pré-engagées : Définition
Defines spending linked to contracts that are difficult to renegotiate in the short term.
Passages and scope
Definition updated on 7 August 2026.
Definition and list: housing, water/energy, telecommunications, canteens, television, insurance and financial services.
The national-accounts concept includes imputed rent and imputed financial services; it differs from a bank-debit list or a list of essential needs.
- L’essentiel sur… l’inflation
Clarifies housing consumption versus investment, basket updates and like-for-like price comparisons.
Passages and scope
Published on 23 March 2026; annual tables mainly cover 2000–2025.
Sections on housing coverage, perceived inflation, new products and measurement.
The annual figures stop in 2025; R02 and R03 supply the 2026 monthly releases.
- Indice des prix à la consommation : les changements de l’année 2026
Documents weights valued at December 2025 prices, the new classification and historical-series treatments.
Passages and scope
Base 2025 and eCOICOPv2 from January 2026; backcasting to 1996.
Updating 2026 weights; backcasting weights and indices.
Changing the numerical reference base and changing classification are distinct operations. Older series are backcast using separate methods for 1996–2015 and 2016–2025.
This analysis is not investment advice.
// cite this analysis
l0g, “Why your budget tells a different inflation story”, l0g.fr, published October 30, 2026, updated October 30, 2026, https://l0g.fr/en/analysis/why-your-budget-tells-a-different-inflation-story/
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