What compound interest is
Compound interest means your balance earns returns, and then those returns can earn returns too. Over long time periods, that compounding effect can make a large difference compared with simple one-time growth.
Finance calculator
Compound Interest Calculator
Estimate how your money could grow with compound interest, recurring contributions, and optional inflation-adjusted insights. The unified form keeps the main inputs, contribution settings, and inflation assumptions together in one clean layout.
Editor
Investment assumptions
Review your main projection inputs, contribution settings, and inflation assumptions in one clean form.
Inputs
Everything on the left updates the projection instantly, with the most important inputs first and supporting assumptions grouped underneath.
Basic inputs
Set the core values that drive the main compound growth projection.
Contribution settings
Fine-tune how often you add money and whether those contributions grow over time.
Inflation
Add an inflation assumption if you want to compare the future balance with today's purchasing power.
Contributions are added at the end of each selected contribution period. If you set an annual contribution increase, the new amount starts at the beginning of each new year.
Results
Projected growth
Results update instantly as you adjust your assumptions, so you can compare scenarios without reloading the page.
Final balance
$144,573
After 20 years with 7% annual growth compounded monthly.
Total contributions
$58,000
Includes your starting amount plus all recurring contributions.
Total interest earned
$86,573
Growth generated by compounding instead of direct deposits.
Growth multiple
2.49x
Final balance divided by the dollars you personally contributed.
Contribution cadence
Monthly
Contributions stay level across the full projection.
Balance growth over time
The dark line shows projected balance growth, while the dashed line shows how much of the total comes from your own contributions.
Total balance
Cumulative contributions
$144.6K$72.3K$0
Year 0Year 10Year 20
Yearly breakdown
Review how each year's starting balance, new contributions, and earned interest combine into the ending balance.
| Year | Starting balance | Contributions | Interest earned | Ending balance |
|---|---|---|---|---|
| 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 works
What this compound interest calculator helps you understand
This calculator estimates how an investment can grow when you start with an initial balance, keep contributing over time, and let interest compound. It is designed to stay approachable for beginners while still being detailed enough for more realistic planning.
How this calculator works
The calculator models growth across your selected number of years, using the compounding frequency you choose and adding recurring contributions at the end of each contribution period. The chart and yearly table are built from the same projection data so the summary cards, chart, and table stay in sync.
Why recurring contributions matter
Small, steady deposits can have a meaningful effect because each new contribution gets more time in the market. Even if your starting amount is modest, consistent monthly or yearly additions can drive a large share of the final balance.
Inflation-adjusted results
If you add an inflation rate and enable the toggle, the calculator also shows a real-value estimate. That helps answer a different question: not just how large the future balance looks in dollars, but what that balance may be worth in today's purchasing power.