Free tool
Simple interest calculator
Updated November 6, 2026. Runs entirely in your browser; nothing you type is sent anywhere.
Enter a principal, an annual interest rate, and a time in years. You'll see simple interest I = P × r × t, the total with interest, and one calm sentence you can adapt. This is arithmetic only—not a loan quote, not an APR disclosure, and not financial advice.
How to use the number
- Use years for t (0.5 = six months). Re-run if the rate is quoted for a different period.
- For compounding over time, see the free compound interest calculator. For loan payments, see the loan payment calculator or debt payoff calculator.
- When the hard part is the bill, raise, or offer call that funds the principal, use a script.
What to say when cash or pay is the bottleneck
Knowing the interest sketch is step one. Saying the next line on a bill, raise, or offer call is where people freeze. The Bills Kit ($19) gives word-for-word lines for bill moments plus Call Mode. If pay is the lever, see the Offer Kit ($29). One-time purchase, 14-day refund on both.
Get the Bills Kit, $19 Get the Offer Kit, $29
How does simple interest work?
Simple interest is I = P × r × t, where P is principal, r is the annual rate as a decimal, and t is time in years. Total with interest ≈ P + I. It does not compound: interest is not added to principal for later periods.
How is this different from compound interest?
Compound interest adds earned interest back so later periods grow on a larger base. Simple interest does not. For compounding sketches, see the free compound interest calculator.
Is this a loan quote or financial advice?
No. It is simple arithmetic on the numbers you enter, plus a sample sentence you can adapt. It is not a credit decision, APR disclosure, tax advice, or a substitute for a qualified professional.
What time unit should I use?
Enter years (for example 0.5 for six months, 2 for two years). The formula on this page uses annual rate × years.
Guidance only, not legal, financial, or tax advice. The calculator does simple arithmetic on the numbers you enter.