How to use Simple & Compound Interest Calculator

1. Prepare the required inputs

Compare simple interest and compound interest with a chosen compounding frequency. Use the units and options beside each field. Results update as inputs change; reset returns to example inputs.

Interest model: Simple / Compound
Starting amount: minimum 1, maximum 1000000000000
Nominal annual interest (%): minimum 0, maximum 100
Term (years): minimum 0.01, maximum 100
Compound frequency: Annually / Semi-annually / Quarterly / Monthly / Daily

2. Try a worked example

10,000 at 5% simple interest for one year earns 500.

3. Understand the calculation

Simple: A = P(1 + rt). Compound: A = P(1 + r/n)ⁿᵗ.

4. Read the assumptions

No additional deposits, taxes or fees. The compounding frequency affects compound mode only; daily uses 365 periods per year.

5. Check and compare results

Match entered values to their labels and units. Review output labels alongside the assumptions, then change one input at a time. A currency selector changes display labels without converting amounts. Use the available save or copy actions and retain the input values so the estimate can be reproduced.

6. Fix an invalid input

Complete required fields and respect the listed bounds. Check date order, age relationships and mode-specific requirements where relevant; the error message identifies invalid combinations. Reset to example inputs to recover. A valid calculation applies to its stated model and does not verify a real-world outcome.