Credit calculator with early repayment online

What the loan (mortgage) calculator is for

The calculator builds a schedule of monthly payments, each made of principal and accrued interest. It shows the total overpayment by the end of the term and the remaining debt on any date, for example if you plan a partial early repayment. After an early repayment you can either lower the monthly payment (same term) or shorten the term (same payment).

Interest is calculated the way banks do it: on the outstanding balance for the actual number of days between payments (rate ÷ 365 or 366 × days). That is why February and March payments differ slightly even with the same balance.

Annuity vs differentiated payments

• Annuity — the same payment for the whole term. Early on most of it goes to interest, later to principal. Payment: P = S × i / (1 − (1 + i)−n), where S is the loan amount, i the monthly rate (annual ÷ 12 ÷ 100), n the number of months.
• Differentiated — the principal is repaid in equal parts (S / n) and interest is charged on the decreasing balance. The first payment is the largest, then payments go down. Less overpayment, but the first months are harder on the budget.
• No monthly payments — a mode to get the balance and interest on any date when you pay irregularly.

Worked example

A loan of 1,200,000 for 12 months at 12% a year, issued on 15.01.2026, payments on the 15th starting in February.

By the annuity formula: i = 12 / 12 / 100 = 0.01, P = 1,200,000 × 0.01 / (1 − 1.01−12) = 106,618.55. The differentiated scheme saves 1,382.32 here; on a 20–30 year mortgage the difference reaches hundreds of thousands.

Early repayment: lower payment or shorter term

Suppose you are already repaying the loan and have spare money. Add the “+ Early repayment” event with a date and an amount. Then there are two options:

• Lower the payment (recalculation on) — the term stays, the monthly amount goes down.
• Shorten the term (no recalculation) — the payment stays, the loan is closed earlier. Overpayment is lower.

In the example above, pay an extra 300,000 on 15.07.2026:

Shortening the term almost always saves more; lowering the payment is safer for the budget. The earlier you repay, the bigger the saving.

Commissions

• One-time — paid once at issue (application fee, account opening): a percentage of the loan or a fixed amount. 1% of 1,200,000 adds 12,000 to the overpayment.
• Monthly — a percentage of the loan, of the remaining debt, or a fixed amount in every payment (account service, insurance).
• Balloon payment — an amount repaid with the last payment (as in car loans with a final buy-out payment).

Total overpayment

The “Total” row shows the principal repaid, the interest, the commissions and the total amount. Overpayment = interest + commissions. With a 1% one-time commission in the example: 79,069.99 + 12,000 = 91,069.99 on top of the 1,200,000 received. With early repayments the calculator also shows the approximate saving.

How to calculate

• Enter the loan amount, term (months or years), interest rate (per year or per month) and payment type. Works for any loan: consumer, car, mortgage.
• Add commissions if any, and the “Monthly payment” field if the bank quoted its own rounded amount, so the schedule matches the bank's to the cent.
• Set the issue date, the payment day and the month of the first payment. For example, the loan is issued on 7 May and you prefer to pay on the 20th after payday: the first payment is 20 May or 20 June. If you start next month, the interest for the first days can be skipped, charged separately or added to the first payment, as your contract says.
• Payments can be allowed on working days only: those falling on a weekend move to the next working day.

Events: early repayment, rate change, deferral

• + Early repayment — partial or full repayment on a date, lowering the payment or the term.
• + Change payment — from a date you pay more (or less) than required: the term is recalculated.
• + Change rate — a new rate after refinancing or under the contract.
• + New payment day — moves the payment day.
• + Deferral — marks a day as a weekend, a working day or a payment holiday.

You can add any number of events; they are applied in date order.

Saving, link and Excel

• After the calculation you get a direct link: it opens the calculation for you or anyone you send it to. An unsaved calculation is deleted after 7 days, a saved one if it is not opened for 100 days.
• A calculation can be edited and saved again, or deleted.
• The “Download in Excel” button exports the whole schedule to an .xlsx file, handy for printing or comparing with the bank's schedule.

If the numbers differ from the bank's

All banks use a similar formula. If the difference is noticeable, check insurance and commissions, how interest for the first month is charged, moving payments off weekends and payment rounding (enter the bank's amount in “Monthly payment”).