How to use this calculator
- Enter starting amount, annual simple rate (%), number of years.
- Choose a display currency, then select Calculate. Results also update after a brief pause while you edit.
- Read the result with the assumptions below. Export details or save a second scenario to compare your choices.
Formula and method
I = P × j × t; ending amount = P + I.
Assumptions and limitations
Interest is not reinvested. Years are entered directly; no automatic actual/365, actual/360 or calendar-day convention is implied.
Worked example
A 1,000 principal at 5% simple annual interest for three years earns 150 and ends at 1,150.
What the result means
A simple rate produces a straight-line gain or loss. Check the contract before using it for a loan or deposit with compounding.
Common questions
Is simple interest compounded?
No. Each period uses the original principal.
What does a fractional year mean?
It is the fraction of an annual period you enter, rather than an inferred bank day-count rule.
Methodology and transparency
Calculation specification reviewed on 2026-10-14. Mathematical implementation is tested against independent reference fixtures. This does not imply review by a licensed financial professional. Read the testing and precision policy.