A credit card balance is repaid at the monthly rate equivalent to the APR, applied each month to whatever is still owed. At 14.5 %, €1,500 repaid €100 a month costs €153.74 in interest and takes 17 payments. The calculator below reruns that sum on your own figures.
Carried balance calculator
What a credit card balance costs, and how long it lasts, when you repay it in monthly instalments.
€
The amount owed on the card today, in euros.
%
Default 14.5%: the legal maximum APR for a credit line used by card, from €1,250 to €5,000 (FPS Economy, in force since 1 June 2025, checked on 30/09/2026). Replace it with the APR printed on your contract or statement.
How do you repay?
€
The amount you pay each month, in euros.
months
In months. Legal maximum: 60 months for a line up to €5,000, 96 months above (Royal Decree of 14 September 2016, article 14). The deadline in your specific terms is often shorter, and that is the one that counts. Enter the time remaining: it runs from the first use after the balance last returned to zero.
Result
Equivalent monthly rate1.135 %
Repayment period17 months (1 yr 5 mo)
Total interest€153.74
Total repaid€1,653.74
First paymentof which €17.02 interest and €82.98 principal€100.00
Balance at zero after 17 months, within the 60-month zeroing deadline.
Fixed monthly payment that clears the card in 60 months: €34.61.
Assumptions
- Monthly rate = (1 + APR)^(1/12) − 1, over a standard month of 365/12 days (Directive 2008/48/EC, Annex I).
- No new spending on the card during repayment.
- APR constant throughout. A variable rate can change along the way.
- No annual fee, no late fees, no cash withdrawal. Payment at the end of each month.
How do you calculate the interest on a carried balance?
In three steps, repeated every month down to the last euro.
- Convert the annual APR into its equivalent monthly rate: i = (1 + APR)^(1/12) − 1.
- Apply that rate to the remaining balance: interest for the month = balance × i.
- Add that interest to the balance, then subtract the month's payment.
The balance that comes out becomes the base for the next month. As long as the payment exceeds the month's interest, the debt goes down; the share that actually repays principal grows with every instalment, because the interest is charged on an ever smaller balance.
The monthly rate formula is not a house convention. It follows from the APR equation laid down in Annex I of Directive 2008/48/EC, carried into Book VII of the Belgian Code of Economic Law: time intervals are expressed there as fractions of a year, with a standard month of 365/12 days, or 30.41666 days. A 14.5 % APR therefore corresponds to 1.1348 % a month, no more and no less.
I spent seven years recalculating statements disputed by cardholders. In the vast majority of files, the issuer's calculation was right. The gap came from elsewhere: a forgotten purchase, a cash withdrawal, a payment cut back to the minimum without the cardholder remembering it.
Why not simply divide the APR by twelve?
Because the APR is already an effective rate, compounded over the year. Dividing it by twelve amounts to applying a rate that is too high.
The figure to remember: 14.5 divided by 12 gives 1.2083 % a month. Compounded over twelve months, that monthly rate produces an APR of 15.50 %, a full point above the contract's. On €1,500, the first month would cost €18.13 instead of €17.02.
The opposite mistake exists too. A contract that shows an actuarial borrowing rate next to the APR gives you a rate that is already effective and annual, but excludes fees; it converts with the same formula. If you enter that borrowing rate instead of the APR, the calculator works out the interest alone, without the fees the APR includes.
Worked example: €1,500 at 14.5 %, repaid €100 a month
The most common case on my desk: a large purchase put on the card, then repaid in fixed instalments. Here is the calculation done by hand, with no new spending.
- Monthly rate: (1.145)^(1/12) − 1 = 1.1348 %.
- Month 1: €1,500 × 1.1348 % = €17.02 of interest. Of the €100 paid, €82.98 repays principal. Balance: €1,417.02.
- Month 2: €1,417.02 × 1.1348 % = €16.08 of interest, €83.92 of principal. Balance: €1,333.10.
- Month 16: only €1.72 of interest is left in the €100 payment. Balance: €53.14.
- Month 17: €53.14 plus €0.60 of interest, for a last payment of €53.74.
Total paid: 16 payments of €100 and one of €53.74, or €1,653.74. Interest comes to €153.74, a little over 10 % of the amount borrowed, for a repayment lasting one year and five months. The same formula in closed form gives n = ln(100 / 82.98) / ln(1.011348) = 16.5 payments: sixteen full payments and a final partial one.
How long does it take to pay off a credit card?
The monthly payment decides almost everything. The APR only shifts the duration by a few months. The table below covers a €2,000 balance, with no new spending.
| APR | €50 a month | €100 a month | €200 a month |
|---|---|---|---|
| 9.5 % | 48 months · €393 interest | 22 months · €177 | 11 months · €88 |
| 12.5 % | 52 months · €556 | 23 months · €239 | 11 months · €116 |
| 14.5 % | 54 months · €681 | 23 months · €281 | 11 months · €135 |
| 16.5 % | 57 months · €821 | 24 months · €325 | 11 months · €154 |
Calculations made on 30 September 2026 with the method described above, amounts rounded to the euro.
Read column by column, the table says something brochures keep quiet. Going from 16.5 % to 9.5 % saves €148 of interest at €100 a month. Going from €50 to €100 a month, at the same 14.5 % APR, saves €400. The lever in your hands is the monthly payment.
Why can the minimum payment overrun the zeroing deadline?
Because a minimum expressed as a percentage of the balance falls as the balance falls. The debt does not close: it flattens out, then drags along at the floor.
Zeroing is the Belgian obligation to bring the balance of a credit line back to zero within a deadline set in the contract. Article 14 of the Royal Decree of 14 September 2016 caps that deadline at 60 months for a line up to €5,000 and at 96 months above that (annotated text of articles 13 and 14). Issuers often set it shorter: Beobank announces a deadline of 22 to 94 months depending on the line and the rate, and a minimum repayment of 1/18 or 1/20 of the amount used, with a minimum of €25 (page published on 9 December 2024, checked on 30 September 2026).
Second case checked by hand: €3,000 at 14.5 %, minimum of 1/18 of the remaining balance, €25 floor. The first payment is €166.67, of which €34.04 is interest and €132.62 principal. Each month, the balance is multiplied by 1.011348 then cut by one eighteenth, a factor of 0.955792. It drops below €450, the point where 1/18 falls under the €25 floor, in month 43. The rest is repaid at €25 a month: €54.15 is still owed in month 60, and the balance only reaches zero in month 63. Total interest: €710.78.
| Starting balance | First payment | Time to zero | Total interest |
|---|---|---|---|
| €500 | €27.78 | 23 months | €69 |
| €1,000 | €55.56 | 38 months | €197 |
| €2,000 | €111.11 | 54 months | €454 |
| €3,000 | €166.67 | 63 months | €711 |
| €5,000 | €277.78 | 74 months | €1,224 |
Minimum of 1/18 of the remaining balance, €25 floor, 14.5 % APR, no new spending. Calculations made on 30 September 2026.
Above roughly €2,750, this pace falls outside the 60-month cap. As a rule, the contract then raises the payments to meet the deadline. One Belgian issuer says so in black and white in its explainer on zeroing: contractual minimum repayments may not be enough to clear the line by the scheduled date. If you do not keep up, the card is blocked and the default can be recorded in the Central Individual Credit Register of the National Bank.
Which APR should you enter if you do not know yours?
The one on your statement or in your specific terms, always. Failing that, the legal cap gives the upper bound.
| Amount of the credit line | Maximum APR, line used by card | Maximum APR, without card |
|---|---|---|
| Up to €1,250 | 16.5 % | 12.5 % |
| €1,250 to €5,000 | 14.5 % | 11.5 % |
| Over €5,000 | 13.5 % | 11.5 % |
Caps in force since 1 June 2025 and left unchanged by the revision of 1 December 2025, according to the overview of maximum APRs published by the FPS Economy, checked on 30 September 2026. The cap depends on the amount of the credit line granted, not on today's balance.
The calculator uses 14.5 % by default because it is the cap for the bracket where most card-linked cash reserves sit. An APR entered above 16.5 % triggers a warning: it exceeds every Belgian legal cap for a credit line used by card.
Which mistakes skew the result?
The calculator is accurate on what it assumes. Gaps with your statement almost always come from here:
- carrying on paying with the card during repayment: every purchase is added to the balance and resets the count;
- a cash withdrawal, which often carries its own fee and interest from the day of the withdrawal;
- the annual fee, charged to the line once a year and left out of the calculation;
- a variable rate, which the issuer can change along the way within the limits of the contract;
- day-by-day interest: an issuer that counts interest over the actual days of a 31-day month drifts a few cents from the standard month;
- mixing up borrowing rate and APR, which drops the fees out of the calculation.
An estimate is not a statement. If your statement and the calculator differ by more than a few euros, ask the issuer for a written breakdown: it has to explain it to you.
What if the monthly payment is no longer enough?
Raise it with the issuer, in writing, before the incident. A spreading arrangement can be discussed as long as the contract is not in default.
I do not give advice on a situation I do not know. Three doors exist, all free: an approved debt mediation service, your municipality's CPAS/OCMW, and Ombudsfin for a dispute with the issuer, after a written complaint that went unanswered or unresolved. None of them involves taking out a new credit to repay the old one.
The mechanics of interest, APR against borrowing rate and Belgian issuers' rates are detailed in the article on credit card interest. The ranking of Belgian credit cards sets out annual fee, APR and withdrawal cost card by card, and the comparison tool puts them side by side.
Sources. Monthly rate formula: basic APR equation and standard month of 365/12 days, Directive 2008/48/EC, Annex I, carried into Book VII of the Belgian Code of Economic Law. Maximum APRs on credit lines: Royal Decree of 14 September 2016, articles 11 and 12, overview published by the FPS Economy (document dated 1 December 2025, caps in force since 1 June 2025), checked on 30 September 2026. Maximum zeroing deadlines: Royal Decree of 14 September 2016, article 14, commentary on articles 13 and 14, checked on 30 September 2026. Example of an issuer's minimum repayment and zeroing deadline: Beobank, page dated 9 December 2024, checked on 30 September 2026; possible shortfall of contractual minimums: Buy Way explainer on zeroing, checked on 30 September 2026. Central Individual Credit Register: National Bank of Belgium. All calculations on this page were made on 30 September 2026. No link in this article is paid.
Comparator
Compare cartes de crédit side by side.
Compare now →
Frequently asked questions
Delphine a passé sept ans au service litiges et rétrofacturation d’un émetteur de cartes belge, à Liège, entre 2015 et 2022 : le bureau où atterrissent les contestations de porteurs, les retraits facturés deux fois et les cautions d’hôtel qui restent bloquées trois semaines. Elle a donc lu, ligne par ligne, plusieurs milliers de relevés de cartes belges, et elle sait où se logent les montants que personne ne regarde avant de signer. Depuis 2023 elle relève chaque trimestre les tarifs publiés des émetteurs belges et tient le tableau de coûts qui sert de base à ce site. Ce qui l’agace : les brochures qui annoncent une carte à 0 € sans mentionner que le premier retrait au distributeur coûte 5 € fixes plus 1,8 % de commission, et que les intérêts courent dès le jour du retrait.