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Current for 2026How we verify data: Methodology →
Equal and decreasing instalments calculator
Compare two types of loan instalments: equal (annuity) and decreasing. Enter the amount, interest rate and term — the calculator works out the total cost and the schedule.
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How we calculate the instalments
Equal instalment: R = P × r(1+r)^n/((1+r)^n−1). Decreasing instalment: capital part = P/n; interest = remaining capital × r.
Example: 300 000 zł, 7%, 25 years
Equal instalment: 2 120 zł/month. Decreasing instalment: starts at 1 750 zł, ends at 83 zł. Interest saving with decreasing: about 80 000 zł.
Frequently asked questions
What is an equal (annuity) instalment?
It is a fixed monthly payment for the whole loan term, with the interest share falling and the capital share rising over time.
What is a decreasing instalment?
The capital part stays constant while interest falls, so payments are highest at the start and decline each month.
Which type is cheaper overall?
Decreasing instalments usually cost less in total interest, because the balance is paid down faster.
Why choose equal instalments?
Equal instalments offer lower, predictable payments at the start, which can be easier to fit into a budget.
Does the schedule change with rate changes?
Yes, for variable-rate loans a change in interest rate alters the instalment amount or the loan term.
Are commissions included here?
No, this calculator covers principal and interest only; add commissions and insurance separately for the full cost.
Result is indicative. It does not include loan commissions and insurance.
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