Loan calculator
The loan calculator takes your loan amount, interest rate and repayment term and works out the monthly annuity payment, the total amount repaid and the final overpayment in interest. It is handy when comparing consumer-loan offers, checking how a payment fits your budget, or seeing how much a loan really costs on top of the borrowed principal.
How the loan payment is calculated
The calculator uses annuity repayment — you pay the same monthly instalment for the whole term, while the split between interest and principal gradually shifts. Early on, more of the payment goes to interest; later, more goes to principal. It needs three inputs: the loan amount (principal P), the annual interest rate and the term in years.
The annual rate is converted to a monthly interest i (rate divided by 12) and the term to a number of payments n (years times 12). The monthly payment is then found with the standard annuity formula:
payment = P × i ÷ (1 − (1 + i)−n)
- Monthly interest: annual rate ÷ 12.
- Number of payments: years × 12.
- Substitute into the annuity formula → monthly payment.
- Total repaid = payment × number of payments; overpayment = total − principal.
Worked example step by step
Take a loan of 200,000 CZK at an interest rate of 8.9% p.a. repaid over 5 years (that is 60 monthly payments).
| Step | Item | Calculation | Amount |
|---|---|---|---|
| 1 | Monthly interest (i) | 8.9% ÷ 12 | 0.7417% |
| 2 | Number of payments (n) | 5 × 12 | 60 |
| 3 | Monthly payment | 200,000 × 0.007417 ÷ (1 − 1.007417⁻⁶⁰) | 4,142 CZK |
| 4 | Total repaid | 4,142 × 60 | 248,518 CZK |
| 5 | Overpayment (interest) | 248,518 − 200,000 | 48,518 CZK |
Over five years you therefore repay roughly 248,518 CZK in instalments and overpay about 48,518 CZK in interest on top of the borrowed 200,000 CZK.
What affects the result
- Loan amount — a larger principal raises both the payment and the total overpayment proportionally.
- Interest rate — even a small difference in percentage adds up to thousands of crowns on longer loans.
- Repayment term — a longer term lowers the monthly payment but raises the total overpayment, because interest accrues for longer.
- Repayment type — the calculator assumes an annuity (equal payment); degressive or lump-sum repayment gives different numbers.
When the loan calculator helps and what to watch out for
Use it for a quick comparison of offers or to estimate whether a payment fits your budget. The result is indicative and based on the pure interest rate. It does not include the APR — that is, arrangement fees, account maintenance, payment-protection insurance or other costs that raise the true price of the loan. To compare specific products, always rely on the stated APR and the contract terms of the given bank or non-bank lender. The calculator also assumes a fixed rate for the whole term and regular monthly payments with no deferrals or extra repayments.
⚠️ Indicative calculation, rates current for 2026. Not a substitute for an accountant or tax advisor — verify important decisions with the Czech Financial Administration.
FAQ
What is the monthly payment on a 200,000 CZK loan over 5 years?
At a rate of 8.9% p.a. with annuity repayment, the monthly payment is about 4,142 CZK. Over 60 months you repay around 248,518 CZK in total, of which interest is roughly 48,518 CZK.
What is an annuity payment?
An annuity payment is a fixed monthly amount for the whole repayment term. Only its internal split changes — at first you pay more interest, later more principal. Our calculator computes exactly this most common repayment type.
Does the calculator include APR and fees?
No. The calculator works only with the interest rate, principal and term. Arrangement fees, account maintenance or insurance are not included. The true cost of the loan is shown by the APR, which you find in the lender's offer.
How do I reduce the total interest overpayment?
Reduce the overpayment with a shorter term, a lower interest rate or extra principal repayments. A shorter term raises the monthly payment but sharply lowers the total interest paid.
What is the difference between a loan and a mortgage?
A consumer loan usually has a higher rate, shorter term and smaller amounts and is not secured by property. A mortgage is secured by a property lien, has a lower rate and longer maturity. For a mortgage, use our mortgage calculator.
What does p.a. mean on the interest rate?
The abbreviation p.a. (per annum) means "per year". A rate of 8.9% p.a. is the annual interest; the calculator converts it to a monthly rate by dividing by twelve to find the monthly payment.
Can I repay the loan early?
With consumer loans you have a statutory right to early repayment. The lender may charge a limited cost compensation. Repaying the principal early lowers the total interest paid compared with this calculator's result.
Is the calculator result binding?
No, it is an indicative estimate. Binding figures, including the APR and all fees, are found only in a specific offer and contract from a bank or non-bank lender.
Sources & legislation
📅 Last updated: 11 July 2026