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GuidesFinanceInterestLoan interest — how to calculate

Loan interest — basics

Calculate in 30 seconds

Use our calculator — result in seconds, no registration required.

Interest calculator — calculate interest amount

Table of contents

  • How to calculate loan interest
  • Contractual interest and legal limits
  • Capitalization
  • Practical scenarios
  • Partial payments
  • Common mistakes
  • Frequently asked questions (FAQ)

Loan interest results from the contract but must stay within legal limits. This guide explains how to calculate it and what to watch for.

How to calculate loan interest

amount × annual rate × number of days / 365

Use the loan interest calculator for a quick estimate.

Contractual interest and legal limits

Parties can agree on interest, but maximum legal caps apply.

Capitalization

If the contract provides capitalization, interest becomes part of the principal. The calculator assumes simple interest.

Practical scenarios

  • Private loan: calculate from payout to repayment.
  • Business loan: follow the contract’s rate and period.

Partial payments

Interest is calculated on the remaining balance after partial repayment.

Common mistakes

  • wrong base amount,
  • rate above legal limit,
  • missing the calculation period.

Try it in practice

Use our calculator — result in seconds, no registration required.

  • Interest calculator — calculate interest amount
  • Tax interest calculator — arrears interest
  • ZUS interest calculator
  • Loan interest calculator
  • Bank interest calculator — deposits & capitalization

Frequently asked questions (FAQ)

Jak obliczyć odsetki od pożyczki?+
Stosuje się wzór: kwota × stopa roczna × liczba dni / 365.
Czy można ustalić dowolną stopę procentową?+
Nie, obowiązują odsetki maksymalne.
Czy kalkulator uwzględnia kapitalizację?+
Nie, kalkulator liczy odsetki proste.

Related guides

  • Statutory interest — rates and calculation
  • Interest note — how to issue and calculate
  • Tax interest — rules and calculation
  • ZUS interest — calculation rules
  • Bank interest — deposits and capitalization

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Related calculators

  • Interest calculator — calculate interest amount
  • Tax interest calculator — arrears interest
  • ZUS interest calculator
  • Loan interest calculator
  • Bank interest calculator — deposits & capitalization

Related guides

  • Statutory interest — rates and calculation
  • Interest note — how to issue and calculate
  • Tax interest — rules and calculation
  • ZUS interest — calculation rules
  • Bank interest — deposits and capitalization
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