Compound Interest Calculator
See how a starting balance plus regular contributions grows with compound interest over time.
Future value $144,572.72
Total contributed $48,000.00
Interest earned $86,572.72
| Year | Start | Contributions | Growth | End |
|---|---|---|---|---|
| 1 | $10,000 | $2,400 | $801 | $13,201 |
| 2 | $13,201 | $2,400 | $1,033 | $16,634 |
| 3 | $16,634 | $2,400 | $1,281 | $20,315 |
| 4 | $20,315 | $2,400 | $1,547 | $24,262 |
| 5 | $24,262 | $2,400 | $1,832 | $28,495 |
| 6 | $28,495 | $2,400 | $2,138 | $33,033 |
| 7 | $33,033 | $2,400 | $2,466 | $37,900 |
| 8 | $37,900 | $2,400 | $2,818 | $43,118 |
| 9 | $43,118 | $2,400 | $3,196 | $48,714 |
| 10 | $48,714 | $2,400 | $3,600 | $54,714 |
| 11 | $54,714 | $2,400 | $4,034 | $61,147 |
| 12 | $61,147 | $2,400 | $4,499 | $68,046 |
| 13 | $68,046 | $2,400 | $4,998 | $75,444 |
| 14 | $75,444 | $2,400 | $5,532 | $83,376 |
| 15 | $83,376 | $2,400 | $6,106 | $91,882 |
| 16 | $91,882 | $2,400 | $6,721 | $101,003 |
| 17 | $101,003 | $2,400 | $7,380 | $110,783 |
| 18 | $110,783 | $2,400 | $8,087 | $121,270 |
| 19 | $121,270 | $2,400 | $8,845 | $132,515 |
| 20 | $132,515 | $2,400 | $9,658 | $144,573 |
How it's calculated
Each month the balance earns one twelfth of the annual rate, then the contribution is added. The next month compounds on the larger balance.
Assumptions
- Interest compounds monthly; contributions are added at month end.
Last updated: 2026-08-07
These assumptions follow our general methodology.
Frequently asked questions
What is the difference from simple interest?
Simple interest is paid only on the original principal. Compound interest is paid on the principal plus all previously earned interest, which is why the curve steepens over time.
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