CALBD · Smart Interest Calculator
Simple & Compound Interest Calculator
Calculate simple and compound interest, view detailed breakdowns, and keep a history of your calculations with this modern financial calculator.
Interest settings
Switch between simple and compound interest with one click.
Currency
% p.a.
Years
Current mode:
Simple interest
Simple interest
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Awaiting input
Total amount
—
Principal + interest
Interest share
—
Interest vs principal
Principal share
Interest share
Breakdown & insights
View tables, formulas, history and analytics for your calculations.
| Period | Opening balance | Interest | Closing balance |
|---|
Calculation time: — ms
Total calculations: 0
Simple interest formula
I = P × R × T
Where:
- P = Principal amount (initial investment or loan)
- R = Annual interest rate (in decimal, i.e. % ÷ 100)
- T = Time in years
Simple interest grows linearly with time and is always calculated on the original principal only.
Compound interest formula
A = P × (1 + r / n)n × t
Where:
- A = Future value (principal + interest)
- P = Principal amount
- r = Annual interest rate (decimal)
- n = Number of compounding periods per year
- t = Time in years
Compound interest grows faster because interest is periodically added back to the balance and itself earns interest.
Total saved calculations: 0
Tips
Click any history item to reload its values into the calculator. Use “Add to favorites” to tag important scenarios for quick access.