Compound Interest Calculator
Understand how time, monthly investing, expected returns, and inflation shape long-term wealth.
What this calculator shows
It separates the money you contribute from the growth created by compounding, then discounts the result for inflation so the outcome is easier to compare in today's purchasing power.
Inputs
Adjust the assumptions and watch the outcome update instantly.
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Final nominal value
$660,849
Before inflation.
Inflation-adjusted value
$315,055
Purchasing power today.
Total contributions
$190,000
Money invested.
Investment gains
$470,849
Growth earned.
Growth chart
Nominal value shows the account balance. Inflation-adjusted value estimates what that balance may feel like in today's purchasing power.
Insights
The useful part is not only the final number. It is understanding what created it, what inflation changed, and why time matters.
Contributions vs growth
Your contributions represent 28.8% of the final nominal value. 71.2% of the final nominal value came from investment growth.
Inflation changes the story
Inflation reduces purchasing power by $345,794, or 52.3% of the nominal ending value.
Starting earlier matters
Starting 5 years earlier adds $301,624, bringing the ending value to $962,473. That is a 45.6% difference under the same assumptions.
Year-by-year breakdown
A table makes the chart inspectable and shows how contributions, gains, and inflation-adjusted value change each year.
| Year | Nominal value | Inflation-adjusted | Contributions | Gains |
|---|---|---|---|---|
| 1 | $16,890 | $16,478 | $16,000 | $890 |
| 2 | $24,263 | $23,093 | $22,000 | $2,263 |
| 3 | $32,151 | $29,856 | $28,000 | $4,151 |
| 4 | $40,592 | $36,774 | $34,000 | $6,592 |
| 5 | $49,623 | $43,860 | $40,000 | $9,623 |
| 6 | $59,287 | $51,123 | $46,000 | $13,287 |
| 7 | $69,627 | $58,575 | $52,000 | $17,627 |
| 8 | $80,692 | $66,227 | $58,000 | $22,692 |
| 9 | $92,530 | $74,091 | $64,000 | $28,530 |
| 10 | $105,197 | $82,180 | $70,000 | $35,197 |
| 11 | $118,751 | $90,506 | $76,000 | $42,751 |
| 12 | $133,254 | $99,082 | $82,000 | $51,254 |
| 13 | $148,772 | $107,922 | $88,000 | $60,772 |
| 14 | $165,376 | $117,041 | $94,000 | $71,376 |
| 15 | $183,143 | $126,454 | $100,000 | $83,143 |
| 16 | $202,153 | $136,175 | $106,000 | $96,153 |
| 17 | $222,494 | $146,222 | $112,000 | $110,494 |
| 18 | $244,258 | $156,610 | $118,000 | $126,258 |
| 19 | $267,547 | $167,358 | $124,000 | $143,547 |
| 20 | $292,465 | $178,483 | $130,000 | $162,465 |
| 21 | $319,128 | $190,004 | $136,000 | $183,128 |
| 22 | $347,657 | $201,942 | $142,000 | $205,657 |
| 23 | $378,183 | $214,315 | $148,000 | $230,183 |
| 24 | $410,846 | $227,147 | $154,000 | $256,846 |
| 25 | $445,795 | $240,458 | $160,000 | $285,795 |
| 26 | $483,191 | $254,272 | $166,000 | $317,191 |
| 27 | $523,205 | $268,613 | $172,000 | $351,205 |
| 28 | $566,019 | $283,506 | $178,000 | $388,019 |
| 29 | $611,831 | $298,978 | $184,000 | $427,831 |
| 30 | $660,849 | $315,055 | $190,000 | $470,849 |
How the calculation works
This is an educational model, not a forecast. It uses a steady annual return assumption, compounds monthly, adds contributions at the end of each month, and discounts future value by the inflation rate.
Compounding
Each month, the current balance grows by the monthly equivalent of the expected annual return. The next month starts from that larger or smaller balance.
Inflation adjustment
Future dollars are discounted back to today's purchasing power so the nominal result does not hide the cost of inflation.
Educational use only
Educational purposes only. Calculator results are estimates based on assumptions and user inputs. They are not financial, investment, legal, or tax advice. Investing involves risk, including possible loss of principal. Past performance does not guarantee future results.