Financial calculator
Simple Interest Calculator
Calculate simple interest and total value from principal, rate, and time.
Build your scenario
Use your actual figures where available. The output is an educational estimate based on the assumptions below.
FINANCIAL ESTIMATE
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Simple interest—
Years—
Annual rate—
Results are estimates for education. Actual terms, rates, taxes, fees, compounding, and lender or investment conditions can change the outcome.
How this simple interest calculator works
Simple interest uses I = P x r x t on the original principal only. Interest is not added back to the balance, so the result is smaller than compound interest at the same stated rate and term.
Important: Review the assumptions shown under each input. Changing one assumption can materially change the result.
When to use this calculator
- Estimate interest on a note or example that is defined as simple interest.
- Contrast the same principal, rate and years with the compound-interest calculator.
- Check a textbook-style simple-interest problem. Many consumer loans compound instead.
Related education
Read the guide → Browse all financial guides →
Frequently asked questions
Is this the same as compound interest?
No. Simple interest never earns interest on prior interest. Use the compound-interest calculator for that.
Does the balance grow each year?
No. The rate is applied to the starting principal for the whole term.
Will a lender use this formula?
Only if the product is written as simple interest. Many loans amortize or compound; treat this as an estimate.