Investment Growth Calculator
See how an investment grows over time with monthly contributions, compound interest, tax, and inflation — with a yearly breakdown and a chart. Estimates only, not financial advice.
Runs in your browser — nothing is uploaded
Your assumptions
Growth over time
- Principal
- Contributions
- Net interest
Yearly breakdown
| Year | Start balance | Contributions | Interest | Tax | End balance | End (real) | |
|---|---|---|---|---|---|---|---|
| 1 | 10,000.00 | 2,400.00 | 776.06 | 116.41 | 13,059.65 | 13,059.65 | |
| 2 | 13,059.65 | 2,400.00 | 990.23 | 148.54 | 16,301.35 | 16,301.35 | |
| 3 | 16,301.35 | 2,400.00 | 1,217.15 | 182.57 | 19,735.93 | 19,735.93 | |
| 4 | 19,735.93 | 2,400.00 | 1,457.57 | 218.64 | 23,374.87 | 23,374.87 | |
| 5 | 23,374.87 | 2,400.00 | 1,712.30 | 256.85 | 27,230.32 | 27,230.32 | |
| 6 | 27,230.32 | 2,400.00 | 1,982.18 | 297.33 | 31,315.18 | 31,315.18 | |
| 7 | 31,315.18 | 2,400.00 | 2,268.12 | 340.22 | 35,643.08 | 35,643.08 | |
| 8 | 35,643.08 | 2,400.00 | 2,571.08 | 385.66 | 40,228.50 | 40,228.50 | |
| 9 | 40,228.50 | 2,400.00 | 2,892.05 | 433.81 | 45,086.74 | 45,086.74 | |
| 10 | 45,086.74 | 2,400.00 | 3,232.13 | 484.82 | 50,234.06 | 50,234.06 | |
| 11 | 50,234.06 | 2,400.00 | 3,592.44 | 538.87 | 55,687.63 | 55,687.63 | |
| 12 | 55,687.63 | 2,400.00 | 3,974.19 | 596.13 | 61,465.70 | 61,465.70 | |
| 13 | 61,465.70 | 2,400.00 | 4,378.66 | 656.80 | 67,587.56 | 67,587.56 | |
| 14 | 67,587.56 | 2,400.00 | 4,807.19 | 721.08 | 74,073.67 | 74,073.67 | |
| 15 | 74,073.67 | 2,400.00 | 5,261.22 | 789.18 | 80,945.70 | 80,945.70 | |
| 16 | 80,945.70 | 2,400.00 | 5,742.26 | 861.34 | 88,226.62 | 88,226.62 | |
| 17 | 88,226.62 | 2,400.00 | 6,251.92 | 937.79 | 95,940.75 | 95,940.75 | |
| 18 | 95,940.75 | 2,400.00 | 6,791.91 | 1,018.79 | 104,113.88 | 104,113.88 | |
| 19 | 104,113.88 | 2,400.00 | 7,364.03 | 1,104.60 | 112,773.31 | 112,773.31 | |
| 20 | 112,773.31 | 2,400.00 | 7,970.19 | 1,195.53 | 121,947.97 | 121,947.97 |
This calculator provides estimates for informational purposes only. It is not financial, investment, or tax advice — actual returns, tax treatment, and account rules vary. Consult a qualified professional for decisions specific to your situation.
About this tool
How is this calculated?
Contributions are simulated monthly. Interest is credited based on your chosen compounding frequency (converted to an effective monthly rate), contributions are added at the end of each month, and tax is deducted annually from that year's interest. Everything runs client-side in your browser.
Why does compounding frequency matter?
The same nominal annual rate produces a higher effective return the more frequently it compounds — daily compounding grows slightly faster than annual compounding at the same stated rate, because interest starts earning interest sooner.
How is tax applied?
Tax is applied once per year, on the interest earned that year only (not on your contributions), and is deducted from the balance — modeling a standard taxable account rather than a tax-deferred one.
What does the "real" balance mean?
The inflation-adjusted balance, shown in today's purchasing power rather than future dollars. If you enter an inflation rate, this shows what the final balance would actually be worth compared to money today.
Is this financial advice?
No. This tool provides estimates for informational purposes based on the numbers you enter. It doesn't account for fees, real-world tax rules, market volatility, or your specific situation. Speak with a qualified financial or tax professional before making decisions.
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