Simple interest calculator
Calculator
The calculator needs JavaScript. The tables below give the same numbers for common cases.
How it is worked out
- Simple interest = principal × rate × time.
- $5,000.00 × 0.045 × 3 = $675.00.
- Total = principal + interest = $5,675.00.
| Inputs | Answer |
|---|---|
| Principal: 5000; Annual interest rate: 4.5; Time: 3 | $5,000.00 at 4.5% simple interest for 3 years earns $675.00, for a total of $5,675.00. |
| Principal: 1000; Annual interest rate: 6; Time: 0.5 | $1,000.00 at 6% simple interest for 0.5 years earns $30.00, for a total of $1,030.00. |
| Principal: 25000; Annual interest rate: 3.2; Time: 5 | $25,000.00 at 3.2% simple interest for 5 years earns $4,000.00, for a total of $29,000.00. |
How to use it
Simple interest is calculated only on the original principal: interest = principal × rate × time. $5,000 at 4.5% for 3 years earns $675, for a total of $5,675.
Use compound interest instead when interest is added to the balance and earns interest itself, as in most savings accounts and loans. These are estimates from the numbers you type, not financial advice or an offer; real products add fees and change rates.
Frequently asked questions
What is the simple interest formula?
I = P × r × t, with the rate as a decimal and the time in years.
How is simple interest different from compound interest?
Simple interest never earns interest on interest; compound interest does.
How do I calculate for months?
Enter the number of months divided by 12 as the years.
Method: standard arithmetic shown step by step; no outside data is used. Checked 2026-11-12.
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General information only. Results are plain arithmetic on the numbers you enter; check anything important (money, health, school work) against your own records or the official source.