Simple & Compound Interest Calculator
Compare simple vs compound growth
These are before-tax, before-fee projections for a single lump sum. Real accounts add platform fees, insurance products, withdrawal penalties and taxation, and rates change or are variable. Nothing here is investment, tax or financial advice, and a projection is not a prediction — confirm current rates with the provider and consider a licensed adviser before committing money.
One lump sum, two growth models, and the gap between them is what compounding costs you or earns you. With a principal, an annual rate and a term in years, the simple model adds a flat rate times the years and ignores the interest on the interest, while the compound model applies the rate over a chosen number of compounding periods per year — one, four, twelve or 365. The tool computes both regardless of which one you select and reports what the other would have produced, so you never have to change settings to see the comparison. You also get a growth multiple, which reads faster than the balance figure when comparing products: 1.55x over ten years at 5 percent is easier to compare against 2.36x over thirty than the underlying balances are. No regular contributions, no tax, no fees.
Calculate simple and compound interest side by side with adjustable compounding frequency. See exactly how compounding accelerates savings and loans over time.
Private Simple & Compound Interest Calculator In Your Browser
Simple & Compound Interest Calculator is processed locally with client-side JavaScript. Your files never touch a server, and there is no queue to wait in.
How to use Simple & Compound Interest Calculator
Enter the starting amount in the Principal field.
Type the annual rate as a percentage, then set the number of Years.
Choose Compounding: Annually, Quarterly, Monthly, Daily, or Simple (none).
Read the final balance and interest earned, then compare against the row showing what the other model would have given.
- Both interest models are always computed, so the comparison is available regardless of which one is selected for the headline figure.
- Daily compounding uses a 365-period year, which matches how most institutions quote a daily compounding rate.
- A growth multiple is reported alongside the balance, making two different terms easy to compare at a glance.
- An interest rate of zero is handled without a division by zero, returning the principal unchanged.
- A saver deciding between a fixed deposit paying simple interest and a compounding account checks what each actually yields over the full term.
- A borrower working out what a credit card balance costs at 22 percent annual and monthly compounding sees how quickly it doubles.
- A student demonstrating the difference between simple and compound interest for a maths lesson runs the same figures twice.