Compound Interest Calculator
See how much your money can grow with daily, monthly, quarterly or yearly compounding — including optional regular contributions.
Compound interest is the interest you earn on both your original money and on the interest that money has already earned. This calculator shows exactly how that snowball effect plays out over time: enter your starting balance, an annual interest rate, a compounding frequency and a time horizon, and it instantly returns the future value, your total contributions and the total interest earned.
The math follows the standard compound interest formula A = P(1 + r/n)^(nt), where P is the principal, r is the annual interest rate, n is how often interest is compounded per year and t is the number of years. You can also include a fixed monthly contribution — a great way to model what happens when you invest a little every month, which is how most people build long-term wealth. A year-by-year breakdown table shows your balance growing across the whole period.
The tool is 100% free and runs entirely in your browser: no accounts, no uploads, and your figures never leave your device. Use any currency — the results simply show amounts. Interest here is assumed to be credited as described (no taxes or fees are deducted), so results are ideal for comparing scenarios and planning, not as a guarantee of future returns.
Tip: try comparing the same rate with yearly versus daily compounding — the difference in interest earned can be surprisingly large on long horizons.
Future value
$31,998.32
Total contributions
$22,000.00
Total interest earned
$9,998.32
Effective annual rate: 5.12% · Amounts shown in $ — this calculator works with any currency.
Year-by-year breakdown
| Year | Contributed | Interest | Balance |
|---|---|---|---|
| 1 | $11,200.00 | $539.50 | $11,739.50 |
| 2 | $12,400.00 | $1,168.01 | $13,568.01 |
| 3 | $13,600.00 | $1,890.06 | $15,490.06 |
| 4 | $14,800.00 | $2,710.44 | $17,510.44 |
| 5 | $16,000.00 | $3,634.20 | $19,634.20 |
| 6 | $17,200.00 | $4,666.60 | $21,866.60 |
| 7 | $18,400.00 | $5,813.23 | $24,213.23 |
| 8 | $19,600.00 | $7,079.91 | $26,679.91 |
| 9 | $20,800.00 | $8,472.79 | $29,272.79 |
| 10 | $22,000.00 | $9,998.32 | $31,998.32 |
How to use the Compound Interest Calculator
- Enter the starting balance, or principal, you plan to deposit today (for example, $5,000).
- Type in the annual interest rate as a percentage (for example, 6.5 means 6.5% per year).
- Choose how often interest is compounded: Annually, Semi-annually, Quarterly, Monthly or Daily.
- Enter the number of years the money will grow.
- Optionally add a monthly contribution amount that you deposit at the end of every month (leave at 0 to ignore).
- Read the results: future value, total amount you contributed, and total interest earned — plus the year-by-year table below.
Frequently asked questions
What is the compound interest formula?
The standard formula is A = P(1 + r/n)^(nt), where A is the future value, P is the principal, r is the annual interest rate (as a decimal), n is the number of compounding periods per year, and t is the number of years. This calculator also supports an optional monthly contribution added at the end of each month, which is simulated month by month using an equivalent monthly rate so results stay accurate for any compounding frequency.
What is the difference between compound interest and simple interest?
Simple interest is calculated only on the original principal every period, so it grows in a straight line. Compound interest also earns interest on previously accumulated interest, so the balance grows faster over time. For example, $10,000 at 5% simple interest over 20 years earns $10,000 in interest, while the same amount compounded annually earns about $16,533.
Does the compounding frequency matter?
Yes. The more often interest is compounded, the more interest you earn for the same nominal annual rate, because interest starts earning its own interest sooner. For $10,000 at 6% over 10 years, yearly compounding gives about $17,908, while daily compounding gives about $18,221 — the difference grows with larger amounts and longer terms.
Can I include regular monthly contributions?
Yes. Enter an amount in the monthly contribution field and it will be added at the end of each month during the entire period. This is the best way to model employer-matched retirement plans, brokerage auto-deposits or any 'invest every month' strategy. Note that contributions are assumed to be made at the same nominal rate and earn the same compounding.
Are taxes and fees deducted from the result?
No. The calculator shows gross growth before any income taxes, account fees, inflation or market volatility. Real-world returns vary and past performance never guarantees future results. Use the result for comparisons and planning, and confirm important decisions with a licensed financial advisor.
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