What is the consumer price index?

The Consumer Price Index (CPI) is calculated each month by the Institut national de la statistic et des études économique (INSEE) to measure the general evolution of prices of goods and services consumed by the French. Official Journal. It allows you to adapt your consumption to better control your spending and purchasing power.

The CPI is the measure of inflation. It makes it possible to evaluate the average variation in the prices of products consumed by households, at constant quality.

Consumer price inflation in France in February 2023 stood at +1% month-on-month and at 6.3% year-on-year, fueled by an increase in food prices (+14.8%), services (+3%) and manufactured goods (+4.7%), the Institut national de la statisticienne (INSEE) said in a publication dated 15 March 2023.

The goods and services concerned

Published monthly at Official Journal, the CPI is calculated on the basis of the observation of prices of a basket of fixed goods and services from different sources:

• the collection by field investigators of prices for all products consumed by households throughout France and in all forms of outlets;
• price records on tariffs, internet prices, administrative data, etc. ;
• cash register data collected by retail stores at the time the consumer goes to the cash register (since January 2020). These data relate to industrial, maintenance, hygiene and beauty food products sold in supermarkets and hypermarkets.

Some goods and services are not included because the price development is difficult to observe or because they are included in other indices (e.g. sales of used vehicles between private individuals, antique furniture, antique works of art and carpets acquired mainly for investment purposes, private hospital services, etc.).

The calculation

Insee calculates the price evolution between two periods for each series of goods. The weight of each product in the basket is then weighted according to the average consumption of the French in order to obtain an average change in the price of this basket.

Thus, to calculate the index at 1^er january, divide the price of the basket at that date by the price of the basket at 1^er January of the previous year, then multiply that result by the benchmark set at 100. To obtain the percentage change between the two dates, it is sufficient to subtract 100 from the new index.

In order to allow you to refine this calculation, which will better reflect your lifestyle or consumption, INSEE has created a customized price index simulator where you can choose the weights of 21 groups of products and services (food, rent, health, water, electricity ...) according to your consumption habits.