Simple Interest Calculator
Calculate simple interest on loans, savings, or investments. Determine the interest earned and total amount after a specified period with our easy‑to‑use calculator.
Step 1: Principal & Currency
What is simple interest?
Simple interest is calculated only on the original principal. Formula: I = P × r × t (where r is annual rate, t is time in years).
Step 2: Interest Rate & Time
Understanding time & rate
Enter the annual interest rate as a percentage (e.g., 5 for 5%). Time can be in years or months – we’ll convert automatically.
Simple Interest Results
Summary
Rate Comparison
Growth Over Time
Total amount after interest
$1,150.00
Interest earned: $150.00
Interest earned
$150.00
Annual interest
$50.00
Effective rate
5.00%
Monthly interest
$4.17
Compare interest at different rates
| Annual rate | Interest earned | Total amount | Annual interest |
|---|
Balance growth over time (year by year)
Simple interest formula
I = P × r × t
Interest = Principal × annual rate (decimal) × time (years).
Total = Principal + Interest. The rate you enter is automatically converted to decimal.
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