Simple Interest Calculator
Estimate simple interest and the total amount payable or receivable using principal, annual interest rate and time (years). This calculator uses the standard simple interest formula for transparent results.
Simple Interest Form
Simple Interest Formula
Simple interest is calculated using the formula below. Interest is charged only on the original principal.
Interest = P × r × t / 100
Where:
- P = Principal amount
- r = Annual interest rate (percentage, e.g. 7.5)
- t = Time in years
- Total = Principal + Interest
This calculator also shows a simple year-by-year linear breakdown (interest per year is constant with simple interest).
Snapshot
| Metric | What it Shows |
|---|---|
| Interest Earned | Total simple interest over the period |
| Total Amount | Principal plus interest (amount payable/receivable) |
| Yearly Breakdown | Principal + interest accumulated each year (linear) |
Use this tool for loans or deposits where interest is not compounded. Examples: short-term personal loans with simple interest, or some institutional agreements where simple interest is specified. Enter principal, annual rate and time to see interest, total amount and yearly values.
When to use this calculator
Use it when you need a transparent, non-compounded interest estimate — for quick loan comparisons, simple deposit plans, or when contract terms specify simple interest rather than compound interest.
How it works (plain explanation)
The calculator multiplies the principal by the yearly rate and the number of years, dividing by 100 to get total interest. Because interest is not reinvested, each year accrues the same absolute interest amount, producing a straight-line increase in total value.
Factors that affect results
The main factors: principal, annual interest rate, and time. If interest compounds in your real product, use a compound interest calculator instead — compound interest will generally produce higher totals for the same nominal rate and time.
Frequently asked questions
Is simple interest the same as APR? Not necessarily. APR can include fees and be compounded — confirm the exact definition when comparing offers.
What if time is fractional (months)? You can enter time in years as a fraction (e.g., 6 months = 0.5 years). The formula applies directly.
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Disclaimer: This calculator is for educational purposes only and does not constitute financial advice. Verify figures with your lender or bank for contractual calculations.