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Compound Interest Calculator
Free compound interest calculator: what a starting amount plus monthly savings grows to with daily, monthly, quarterly or yearly compounding, with a year-by-year table and the APY.
Your savings
After 10 years
$47,527
| You put in | $34,000 |
| Interest earned | $13,527 |
| Effective yearly rate (APY) | 5.12% |
Year by year
| Year | Put in | Interest | Balance |
|---|---|---|---|
| 1 | $12,400 | $567 | $12,967 |
| 2 | $14,800 | $1,287 | $16,087 |
| 3 | $17,200 | $2,165 | $19,365 |
| 4 | $19,600 | $3,212 | $22,812 |
| 5 | $22,000 | $4,435 | $26,435 |
| 6 | $24,400 | $5,843 | $30,243 |
| 7 | $26,800 | $7,446 | $34,246 |
| 8 | $29,200 | $9,254 | $38,454 |
| 9 | $31,600 | $11,277 | $42,877 |
| 10 | $34,000 | $13,527 | $47,527 |
Compound interest pays interest on your interest. At 5% a year money doubles in about 14 years (the rule of 72: 72 ÷ rate). Savings account interest is taxed as ordinary income; inside an IRA or 401(k) it grows tax-deferred.
Before tax and fees, at the same rate every year; monthly additions are made at the end of each month. Not legal, tax or financial advice. 🔒 Everything stays on your device.
📚 Official sources: Investor.gov
We build every tool from the official rules and re-check them when they change. Always confirm with the official source before you rely on a result.
🛠️ Spotted a mistake or an out-of-date rule? Tell us
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Questions people ask
How is compound interest calculated?+
Balance = amount × (1 + rate ÷ n)^(n × years), where n is how often interest is added. Monthly savings are added on top.
How long does it take to double my money?+
Divide 72 by the yearly rate: about 12 years at 6%.