How to Use
- 1 Enter your values
- 2 Click the Calculate button
- 3 Get your result instantly
- 4 Reset to calculate again
Interest Calculator
What Is a Compound Interest Calculator?
A compound interest calculator is a free online tool that calculates how your investment or savings grows over time when interest is earned on both your initial principal and accumulated interest. It also compares compound interest vs simple interest side by side so you can see the power of compounding.
Compound Interest
Simple Interest
Common Compound Interest Scenarios
| Initial | Rate | Time | Final Amount |
|---|---|---|---|
| $10,000 | 5% annually | 20 years | $26,532.98 |
| $10,000 | 7% annually | 20 years | $38,696.84 |
| $5,000 | 5% monthly | 10 years | $8,235.05 |
| $1,000 | 8% daily | 5 years | $1,490.90 |
ℹ️ Albert Einstein reportedly called compound interest "the eighth wonder of the world." Starting early matters more than having a high rate — even small contributions in your 20s can grow into significantly larger sums by retirement than larger contributions started in your 40s.
Frequently Asked Questions
What is compound interest?
Compound interest is interest earned on both your initial principal and the accumulated interest from previous periods. This creates a snowball effect where your money grows faster over time. Formula: A = P(1 + r/n)^(nt).
How is compound interest different from simple interest?
Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus accumulated interest. Over time, compound interest produces significantly higher returns than simple interest.
How often should interest be compounded?
The more frequently interest compounds, the more you earn. Common frequencies: annually (1x/year), quarterly (4x/year), monthly (12x/year), daily (365x/year). For the same nominal rate, daily compounding yields the highest return.
What is the rule of 72?
The Rule of 72 is a quick way to estimate how long it takes for an investment to double: divide 72 by the annual interest rate (%). For example, at 6% interest, your money doubles in approximately 72 ÷ 6 = 12 years.
What is the compound interest formula?
A = P(1 + r/n)^(nt) where A = final amount, P = principal, r = annual interest rate (decimal), n = compounds per year, t = years. Use this calculator to compute it instantly without doing the math manually.
Is this compound interest calculator free?
Yes. Free to use with no signup or download required.