Compound Interest Calculator
See how savings grow with compound interest — enter a deposit, monthly contributions and a rate to get the final balance and a year-by-year table.
Each period the balance grows as FV ← (FV + contribution) × (1 + r), with r = annual rate ÷ periods per year (12 / 4 / 1). Contributions are deposited at the start of each period, so each one earns interest from that period on.
Year-by-year growth
| Year | Contributed | Interest | Balance |
|---|---|---|---|
| 1 | $11,200 | $544.62 | $11,744.62 |
| 2 | $12,400 | $1,178.5 | $13,578.5 |
| 3 | $13,600 | $1,906.2 | $15,506.2 |
| 4 | $14,800 | $2,732.53 | $17,532.53 |
| 5 | $16,000 | $3,662.53 | $19,662.53 |
| 6 | $17,200 | $4,701.51 | $21,901.51 |
| 7 | $18,400 | $5,855.03 | $24,255.03 |
| 8 | $19,600 | $7,128.96 | $26,728.96 |
| 9 | $20,800 | $8,529.47 | $29,329.47 |
| 10 | $22,000 | $10,063.02 | $32,063.02 |
This tool runs entirely in your browser. Your data never leaves your device — it is not uploaded to any server.
How to use
- 1Enter the initial deposit and the amount you will add every month (0 for a one-off deposit).
- 2Set the annual interest rate, the number of years and how often interest compounds.
- 3Pick a display currency — amounts are formatted for your locale.
- 4Read the final balance, total contributions and interest earned, then check the year-by-year table.
Compound Interest Calculator
Compound interest is interest on interest: each period the balance earns a share of the annual rate, and every deposit you add starts earning its own interest too. This calculator runs that recursion period by period for an initial deposit plus regular monthly contributions, at monthly, quarterly or annual compounding.
The result is the final balance, the total you put in, and the interest the compounding generated — plus a year-by-year table so you can see exactly when the curve starts to bend. Everything recalculates live, and the formula used is printed right under the numbers, so you can check it against your bank's own projection.
Frequently asked questions
What formula does the calculator use?
The same balance recursion banks use to project savings: each period, balance ← (balance + contribution) × (1 + r), where r = annual rate ÷ periods per year (12 for monthly, 4 for quarterly, 1 for annual). Contributions are deposited at the start of each period, so they earn interest from that period on. Example: 10,000 initial, 100/month at 5% for 10 years with monthly compounding gives a final balance of 32,063.02 — 22,000.00 contributed and 10,063.02 in interest.
Why do I get slightly different results on other calculators?
Timing conventions differ. Some tools treat contributions as end-of-period deposits (they earn no interest in the period they arrive), some assume daily compounding, and some round each period. This tool deposits at the start of each period and never rounds intermediate steps; a 0.1% difference against another site is usually that convention, not an error.
Does it include taxes, fees or inflation?
No — the result is nominal growth at the rate you enter. Taxes on interest, account fees and inflation all reduce the real return, so treat the final balance as an upper bound on what you would actually keep.
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