Simple Interest Calculator
FinanceUse this simple interest calculator to work out interest and the final amount with the standard P × r × t formula — useful for short-term loans and quick planning.
Your estimate
Estimates only — verify important figures with official sources.
How it works
Interest is the principal multiplied by the annual rate and the time in years. The final amount is the principal plus that interest.
Formula
Interest = P × r × t
Final amount = P + Interest
P = principal · r = annual rate · t = time in years
Example calculation
৳100,000 at 7% per year for 3 years:
- Interest ≈ ৳21,000
- Final amount ≈ ৳121,000
Important notes
- This tool does not compound interest — use the compound interest calculator for that.
- Check with the lender whether interest is calculated on a simple or reducing balance.
See the difference with the Compound Interest Calculator with growth chart.
Frequently Asked Questions
Simple interest is calculated only on the original principal: Interest = P × r × t. Unlike compound interest, earned interest is not reinvested.
It is common for short-term loans, some bonds and quick calculations where interest is not compounded.
The final amount is the principal plus the simple interest earned over the period.
Interest = P × r × t, where P is the principal, r is the annual rate as a decimal and t is the time in years. The final amount is the principal plus that interest.
Simple interest results are estimates for general information. Confirm actual terms with the lender or institution.
Last updated: September 2026