Calculate compound interest with optional regular contributions. Choose yearly, monthly or daily compounding and see how your money grows.
| Input | Result |
|---|---|
| $1,000 at 5% for 10 yrs, monthly | $1,647.01 |
| $5,000 at 8% for 5 yrs, yearly | $7,346.64 |
| $1,000 at 5% for 10 yrs, $100/month, monthly | $17,175.24 |
Compound interest is interest earned on both the original principal and on previously accumulated interest, so the balance grows faster over time.
Yes. The more often interest compounds, the higher the final amount for the same nominal rate, monthly compounding beats yearly compounding.
Each contribution starts earning its own compound interest from the moment it is added, so regular contributions can outgrow a larger one-time deposit over long periods.
The single biggest driver of the result is not the rate you type, it is how long the money stays in. Doubling the horizon more than doubles the interest when contributions are flowing in, because every contribution gets its own runway. Run the same numbers at 10, 20 and 30 years and watch the gap widen: that spread is the honest picture of why starting earlier beats saving more.
| Compounding setting | When to use it | Reality check |
|---|---|---|
| Yearly (n=1) | Bonds that pay annual coupons; simple illustrations | Understates what a bank account actually pays |
| Monthly (n=12) | Savings accounts, CDs, most consumer deposits | The default to use for "bank math" |
| Daily (n=365) | Savings accounts that advertise daily compounding | Barely differs from monthly at normal rates |
Maya, 32, has $1,000 saved and can put away $200 a month. Her employer plan is already maxed, so this goes into a taxable savings account she expects to average 4% on. Enter P=1000, rate=4, t=10, n=12, contribution=200: the balance reaches about $30,400, of which roughly $24,000 is her own deposits and $6,400 is interest. Now change only t to 20: about $75,000, with $48,000 deposited, the second decade adds more interest ($27,600) than the first two combined, on the same monthly effort.
For reference when choosing your own rate: the Federal Reserve's H.15 weekly release publishes the actual rates banks pay on savings and CDs, checking it once before you run a long projection beats guessing, and it is the same series our editorial team reviews each quarter.
How this page is built and kept current. Written and fact-checked by the MoneyCalcsHub editorial team. We do not sell financial products and we accept no payment to change a result, the arithmetic on this page runs in your own browser from the numbers you type.
Official sources used on this page:
Source-dependent figures are reviewed when the cited issuer publishes an update. Worked examples show the formula applied to the listed inputs; interactive results are calculated in your browser.
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