Consumer price index: what is the trend?

Consumer prices rise by 0.1% over one month and 0.9% over one year. This slight increase in prices in October 2025 is primarily explained by the rebound in service prices (+0.2% after -1.9%) caused by the seasonal increase in air transport prices (+14.7% after -27.5%). Prices of manufactured goods (+0.2% after +0.4%) also contributed to the overall increase, but to a lesser extent. Conversely, those for food decreased again (-0.2% as in September), as did those for energy (-0.4% after stability). Tobacco prices remain stable, as in the previous month.

The CPI is calculated each month by the National Institute of Statistics and Economic Studies (INSEE) to measure the general evolution of the 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.

It is an instrument for measuring inflation; it allowsassess the average change in the prices of products consumed by households, at constant quality.

The goods and services concerned

The CPI is calculated on the basis of observing the 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 points of sale;
• price collection on tariffs, internet prices, administrative data, etc.;
• cash register data collected by supermarket retailers 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 taken into account because their price evolution is difficult to observe or because they are recorded in other indices (for example, sales of second-hand vehicles between individuals, antique furniture, antique works of art and carpets acquired mainly for investment purposes, private hospital services, etc.).

How is the CPI calculated?

INSEE calculates the price evolution between 2 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 to obtain an average evolution of the price of this basket.

Thus, to calculate the index at 1^er in january, you must divide the price of the basket on this date by the price of the basket at 1^er January of the previous year, then multiply that by the benchmark of 100. To obtain the percentage variation between the 2 dates, it is sufficient to subtract 100 from the new index.

To allow you to refine this calculation, which will better reflect your lifestyle or consumption, INSEE has created a personalized 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.