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Practical guide
Twelve or thirteen months, the hours in your contract, bonuses included or not: a botched conversion makes an offer look better than it is, or worse. The method, the traps, and examples calculated by the site.
One job ad quotes a gross annual salary, another a gross monthly figure “over thirteen months”, a third an hourly rate. Before comparing them, you have to bring them back to the same unit, and that is where mistakes creep in: a forgotten thirteenth month, contract hours that are not 35 a week, bonuses counted in the annual figure but not in the monthly one. This guide gives the conversion rules, examples calculated by the site, and the traps that come up most often in job ads.
A thirteenth month is not a December present: it is an extra month's salary in the year, provided by the collective agreement, a company deal, an established company practice or the contract. It changes everything in a conversion. The examples below are calculated by the site with its period rules, for €2,500 gross paid every month, then for €36,000 gross a year.
| What the ad says | Gross annual | Paid each month | Average monthly (annual ÷ twelve) |
|---|---|---|---|
| €2,500 a month over twelve months | €30,000 | €2,500.00 | €2,500.00 |
| €2,500 a month over thirteen months | €32,500 | €2,500.00 | €2,708.33 |
| €36,000 a year over twelve months | €36,000 | €3,000.00 | €3,000.00 |
| €36,000 a year over thirteen months | €36,000 | €2,769.23 | €3,000.00 |
Two readings of the same “over thirteen months”, then: if the ad gives a monthly figure, the thirteenth month is added and the annual figure climbs; if it gives an annual figure, the thirteenth month is already in it and each month is smaller than the annual divided by twelve. The guide on the thirteenth month explains who is entitled to it and how it is paid.
An hourly rate is converted with the contract's hours, not with a four-week month. For full time at 35 hours, multiply by 151.67 h; the SMIC (minimum wage) illustrates it: since 1 June 2026, €12.31 an hour makes €1,867.02 a month and €22,404.20 a year (source: service-public.fr).
| Gross hourly rate | Gross monthly (151.67 h) | Gross annual (twelve months) |
|---|---|---|
| €13.00 | €1,971.67 | €23,660 |
| €15.00 | €2,275.00 | €27,300 |
| €18.00 | €2,730.00 | €32,760 |
| €22.00 | €3,336.67 | €40,040 |
| €30.00 | €4,550.00 | €54,600 |
If your contract provides 39 hours a week, the month has 169 h; at the hourly SMIC, that would make €2,080.39 a month before any premium: hours beyond the legal working week are overtime, paid at a higher rate, and the guide on overtime gives the rates. Part time follows the same logic with fewer hours, and the full-time-equivalent gross is found by dividing by the share of full time. Under a days-based deal(forfait jours), on the other hand, the salary pays for a number of days in the year, not hours: it is the value of your day that you compare.
“Gross annual: €36,000, bonuses included” is not the same as “fixed pay of €36,000”. In the first case, variable pay, the thirteenth month or the holiday bonus are already in the total, and the fixed monthly figure is lower than the annual divided by twelve; in the second, bonuses come on top. Always ask for the breakdown: fixed, guaranteed or target variable, thirteenth month, other bonuses, and over how many months. The guide on reading a job ad details the wordings you come across (“selon profil”, range, package) and the questions to ask.
Once the gross annual figure is set, net pay is worked out on the average monthly figure. For €2,500 gross paid every month, the site's engine gives an average net of €1,957 a month over twelve months, and €2,122 over thirteen months (i.e. €25,464 of net in the year against €23,485). The hourly, monthly and annual salary tool does all these conversions in gross and net for your hours and months paid, and the gross-to-net converter refines it with cadre status.
Once the units are aligned, the real question remains: does this gross annual figure match your profile? Upload your CV and the site works out what you are worth on the market, in the same unit, ready to set against the offer.
By the number of months actually paid: twelve in most companies, thirteen when the collective agreement or the contract provides a thirteenth month. Divided by twelve, you get the average monthly figure, useful for comparing; divided by thirteen, the amount that arrives each month, useful for your budget. Both are right, they just answer different questions.
Because a year has fifty-two weeks for twelve months, i.e. slightly more than four weeks a month. The legal working week of 35 hours therefore gives 151.67 h a month on average, and that is the figure payslips and collective agreements use, even for a short or a long month.
Yes, for the same monthly figure: thirteen months are worth more than twelve. For €2,500 gross paid every month, the site works out an average net of €1,957 a month over twelve months and €2,122 over thirteen. But for the same gross annual pay, thirteen months change nothing in total: only the spread over the year differs.
Divide the gross by the contract's share of full time: a four-fifths gross, divided by that share, gives back the full-time gross, which is the base for comparisons and job ads. The hourly rate does not change between full time and part time. The part-time salary tool does the conversion both ways.
This guide gives you a method, not legal advice: the official rules and amounts are those of the sources above, as at their date.
The site's tools and features that go with this guide: the figures there are calculated by the code, never by the AI.