TOOLRIFT

Compound Interest Calculator

Calculate how your savings grow over time with compound interest. Supports yearly, half-yearly, quarterly, monthly, and daily compounding.

Maturity amount215,892.5
Principal100,000
Interest earned115,892.5

🔒 100% private — calculations run in your browser. Nothing is uploaded.

About the Compound Interest Calculator

Compound interest is interest earned on both your original deposit and on the interest already added to it. Over long periods this 'interest on interest' effect is what turns modest, regular saving into a large sum — which is why it's often called the eighth wonder of the world.

This calculator applies the formula A = P(1 + r/n)^(nt), where P is the principal, r is the annual rate, n is how often interest compounds each year, and t is the number of years. The more frequently interest compounds — daily versus yearly, for example — the faster your balance grows, so the tool lets you compare compounding frequencies side by side.

Frequently asked questions

What's the difference between simple and compound interest?

Simple interest is calculated only on the original principal, so it grows in a straight line. Compound interest is calculated on the principal plus accumulated interest, so the balance grows faster and faster over time.

Does compounding frequency really matter?

Yes, but with diminishing returns. Daily compounding earns slightly more than monthly, which earns more than yearly, at the same nominal rate. The difference is small over one year but adds up over decades.

How can I use the rule of 72?

Divide 72 by your annual interest rate to estimate how many years it takes your money to double. At 8% a year, money roughly doubles every nine years — a quick sanity check against this calculator's results.

Related finance calculators