Simple Interest Calculator
Calculate simple interest and the total amount from principal, rate and time in years, months or days. Compare it with compound interest. Free.
- Total amount (principal + interest)
- 11,500.00
- Compound interest would be (yearly)
- 1,576.25
The simple interest formula
Simple interest is charged or earned only on the original amount, never on interest already added. The formula is I = P × R × T ÷ 100, where P is the principal, R the yearly rate in percent and T the time in years. 10,000 at 5% for 3 years earns 1,500. Simple interest is used for some car loans, short-term personal loans, bonds and in school maths problems. The calculator also shows what yearly compound interest would earn over the same time, so you can see the difference.
How to use it
- 1
Enter the principal
The amount borrowed or invested.
- 2
Enter the rate and time
The yearly rate and the time in years, months or days.
- 3
Read the interest
See the interest, the total amount and the compound interest comparison.
Frequently asked questions
How do I calculate simple interest for months?
Convert the months to years: 18 months is 1.5 years. 10,000 at 6% for 18 months earns 10,000 × 6 × 1.5 ÷ 100 = 900.
How do I find the rate from the interest?
R = I × 100 ÷ (P × T). If 5,000 earns 600 in 2 years, R = 600 × 100 ÷ (5,000 × 2) = 6%.
Is simple or compound interest better?
For savers, compound interest earns more. For borrowers, simple interest costs less over the same time.
Is anything sent to a server?
No. Everything is calculated in your browser, and nothing you type is stored or sent anywhere.