Car insurance premium calculation: what weighs, in euros

A car insurance premium is a product of coefficients, not a sum of surcharges. On the site's reference profile, the bonus-malus degree alone moves the liability premium from €267 to €1,070, a factor of 4, whereas mileage adds €25 to €189.

How is a car insurance premium calculated?

By multiplication. The insurer starts from a base premium, then multiplies it by a coefficient for each criterion.

The driver counts: age, years since the licence was issued, claims history. The vehicle counts too: power, value, age. Then come use, meaning the maximum mileage and whether the car is private or professional, and finally the address. Argenta publishes this list of criteria citing article 45 of the law of 4 April 2014 on insurance, and none of the documents consulted publishes the coefficients themselves.

This opacity has a practical consequence: you cannot recalculate your own premium, only measure the gap each variable produces from one quote to the next.

Which lever weighs the most, in euros?

The driver's age first, then the bonus-malus degree and the cover level, well ahead of the sales channel or mileage. The table lists the gaps measured on this site, each with its profile and source.

The comparisons do not use the same profile from one line to the next. They rank orders of magnitude; they are not meant to be added up.

Why does a young driver pay up to eight times more?

Because experience is missing and statistics penalise it. Selectra publishes (page consulted on 2 November 2026) the example of an 18-year-old driver in a 61 kW Citroën C3 worth €12,200: €1,265 of liability at ING, €2,147 at Ethias, €2,190 at Yuzzu.

For the same insurer, an adult with a clean record pays €323 at ING, €363 at Ethias and €270 at Yuzzu (grid of 26 January 2026). The ratio therefore runs from ×3.9 to ×8.1. The vehicles differ, so these numbers cannot be read to the cent.

Against that, an at-fault claim weighs little: it costs €535 of surcharge over five years on the reference profile, detailed in the cost of an at-fault claim. For a young driver, the gain comes first from time: young driver car insurance details the years to get through.

How much does the bonus-malus degree weigh in the premium?

A factor of 4 between the best and the worst degree. The 23-degree grid, inherited from the compulsory system abolished in 2004, sets degree 0 at 50 % of the base premium, degree 14 at 100 % and degree 22 at 200 %.

The reference profile pays €353 of liability at degree 6, which is 66 %. The working assumption: the 100 % base is then worth €535.

Each company sets its own scale, and some personalise it: the principle holds, the figures do not. One claim-free year takes degree 6 to degree 5 (63 %), which is €16 less. The effect is slow and cannot be ordered up.

Which criteria may an insurer use?

The list is long, and it is published. Sex has been excluded since 21 December 2012, after the Test-Achats ruling of the Court of Justice of the European Union of 1 March 2011. Here are the ones Argenta says it uses:

• the age of the main and secondary driver, and the years of licence;
• the region of residence;
• the maximum annual mileage and private or professional use;
• the power, catalogue value, age, fuel type and number of seats of the vehicle;
• the bonus-malus degree, the claims history certificate and previous cancellations;
• the chosen deductible and the payment frequency.

The colour of the vehicle is not on that list. Each insurer has its own: ask for yours, Argenta publishes its list citing article 45 of the law.

What should you do, depending on your case?

Act on the lever you control. The table pairs each one with a situation.

Method, reference profile and sources

The site's reference profile: a 35-year-old driver, Volkswagen Golf 1.5 TSI, Flemish Brabant, no claim for five years, about 15,000 km a year. Liability at €353 and full omnium at €1,135: Mon-Assurance-Auto grids (Yago S.A., broker licensed by the FSMA, the Belgian financial services and markets authority, no. 114863), surveyed on 26 January 2026. Liability premiums by insurer (€270 to €486 at 10,000 km, increases of €25 to €189 at 25,000 km) come from the same grid, for a woman born in 1968 in Court-Saint-Étienne: only the gaps and ratios carry over. The 18-year-old's premiums come from the Selectra page consulted on 2 November 2026. The bonus-malus coefficients, the €535 base and the cumulative figures are my own calculations, based on the grid published in our bonus-malus guide.

The list of criteria is the one published by Argenta (document dated 7 April 2024). The legal framework is the law of 4 April 2014 on insurance. In a dispute over a premium or a refusal, the Insurance Ombudsman has jurisdiction; if no insurer will accept you, the Bureau de Tarification sets a premium by default, and the Fonds commun de garantie compensates victims of an uninsured driver. Premium tax, rates and policy fees are detailed in our article on car insurance premium tax. This site compares and calculates: it does not sell insurance, is not an intermediary and gives no individual recommendation. Speak to your insurer or a broker licensed by the FSMA. No link is affiliated.

In short

Age, bonus-malus degree and cover level make up most of the premium; the choice of insurer adds €216 that only you can recover. Run a premium simulation, put offers side by side in the comparison tool and see the ranking of the best car insurers. To estimate the price before a quote, see estimating your premium; for savings, lowering your premium.