How it works
Calculate interest on the original principal only. The annual rate stays fixed; fees, taxes and inflation are excluded.
I = Prt; total = P+I
Worked example
Show example inputs and result
Principal: 10,000 · Annual rate: 8 · Years: 3.
- Final balance
- 12,400
- Interest
- 2,400
Questions and answers
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method reviewed: October 8, 2026 · Methods & accuracy