Simple vs Compound Interest Calculator
For the same principal, annual rate and years, compare the simple-interest and compound (yearly) end values and the gap.
Results
Fill in the inputs and click Calculate.
- Simple End Value
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- Compound End Value
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- Compound − Simple
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- Gap vs Simple %
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Risk disclaimer
The rate is your input assumption — no return is promised; real products carry fees and volatility.
How do simple and compound differ?
Simple interest accrues only on the principal each year — interest earns no interest.
Compound interest adds each year's interest to the principal, so the gap widens with time.
How to use
- Enter the principal.
- Enter the annual rate %.
- Enter the number of years.
- Click Calculate to compare end values and the gap.
Formula
- Simple end = principal × (1 + annual × years)
- Compound end = principal × (1 + annual)^years
- Gap = compound end − simple end
Example
Principal 1,000 at 10% for 10 years → simple 2,000, compound ≈ 2,593.74, gap ≈ 593.74.
Doubling the years or rate usually grows the gap much faster.
FAQ
What compounding frequency?
Yearly here; for monthly or daily compounding use the compounding-frequency tool.
Negative rates?
Both can end below principal and the gap flips sign; the page reports the math faithfully.