Gross / net calculator Belgium
Estimate your monthly net salary in Belgium from a gross figure: ONSS contributions at 13.07 %, the employment bonus (bonus à l emploi, around 3 400 €), and the professional withholding according to your family situation and children. The calculation works both ways, from net to gross as well. A salary is a private figure, and the result stays on your device.
- 100% local
- Free · no account
- Instant result
This tool runs entirely in your browser — nothing is sent to a server.
In Belgium, the gap between gross and net salary comes from three successive deductions. First, the personal ONSS (social security) contribution of 13.07 % of gross (computed on 108 % of gross for blue-collar workers). Then the professional withholding, an advance on income tax that depends on your family situation and dependants. Finally the special social security contribution, capped at a few dozen euros per month.
Low salaries benefit from the employment bonus, a reduction of the personal contributions that decreases as the salary rises and vanishes beyond roughly €3,400 gross. This calculator rebuilds each step and shows the line-by-line detail, in both directions: from gross to net, or from a desired net to the gross to negotiate.
How it works
Type the figures or drop the file you want to process — the tool checks them as you go.
Everything is computed directly in your browser. Nothing is sent to a server.
The result appears instantly, with the detailed breakdown ready to copy, download or keep.
Why use this tool
No account, no download, no limit: the result appears as soon as you enter your data.
Every rule, algorithm and check reflects what we use ourselves every day at Flexina.
The calculations follow the official standards, and the step-by-step detail lets you double-check the outcome.
What does running it locally bring you?
Files, figures and documents never leave your device: nothing is stored, nothing is sent.
Once the page is loaded, you can cut the network: the tool keeps working.
No upload, no account, no third-party server in between: results stay fast and fully private.
Frequently asked questions
Why does my result differ by a few euros from my payslip?
The official professional withholding follows its own monthly tax table (annex III of the CIR92 royal decree), which this tool approximates by annualising your income. The gap is normally a few euros. Also added are elements the calculator ignores: meal vouchers, any-kind benefits, group insurance or your joint committee’s rules.
What is the employment bonus?
It is a reduction of the personal ONSS contributions reserved for low salaries, which increases the net at no extra cost to the employer. It has two decreasing parts — one for very low salaries, the other for low salaries — and disappears beyond roughly €3,400 gross per month. It also grants a reduction of the professional withholding, at a rate specific to each part. Its amounts are revalued several times a year.
Why does a blue-collar worker have a lower net than a white-collar one at equal gross?
The blue-collar worker’s ONSS contributions are computed on 108 % of the gross salary, a flat base that anticipates the holiday allowance paid by the holiday fund. The monthly deduction is therefore higher, but the holiday allowance is received separately.
Are my salary details sent anywhere?
No. The whole calculation runs in your browser: your salary and family situation are transmitted to no server and are not recorded.