Project a starting balance and recurring contributions using an assumed annual return, compounding frequency, tax rate, and inflation rate.
Dated reference: July 2026 U.S. CPI-U 12-month change: 3.36%. Snapshot retrieved 2026-09-10; reference is not a forecast or automatic input.
Value breakdown
Nominal components and adjustment impacts.
Yearly balance trend.
The line shows nominal balance before tax and inflation adjustments. Hover or tap the chart to inspect values.
| Year | Growth | Balance |
|---|---|---|
| 1 | $9,000.00 | $109,000.00 |
| 2 | $18,810.00 | $118,810.00 |
| 3 | $29,502.90 | $129,502.90 |
| 4 | $41,158.16 | $141,158.16 |
| 5 | $53,862.40 | $153,862.40 |
| 6 | $67,710.01 | $167,710.01 |
| 7 | $82,803.91 | $182,803.91 |
| 8 | $99,256.26 | $199,256.26 |
| 9 | $117,189.33 | $217,189.33 |
| 10 | $136,736.37 | $236,736.37 |
| 11 | $158,042.64 | $258,042.64 |
| 12 | $181,266.48 | $281,266.48 |
Showing 12 of 20 yearly rows.
This calculator is for planning estimates only and is not investment advice. Tax and inflation rates are simplified assumptions, not guarantees.
How it works
The formula shows how the investment calculator turns your inputs into the result. Use it to check the calculation, then follow the example steps to see each part of the math.
FV_P = P(1 + r / n)^(n x t)
Use this to calculate growth of the starting balance without recurring contributions.
FV_P= Future value of starting principalP= Starting principalr= Nominal annual return as a decimaln= Compounding periods per yeart= Time in yearsB_m = (B_(m-1) + C_m)(1 + j); j = (1 + r / n)^(n / 12) - 1
This recurrence matches the calculator: add any scheduled contribution at the beginning of the month, then apply the equivalent monthly growth rate.
B_m= Balance after month mB_(m-1)= Balance after the previous monthC_m= Contribution scheduled at the beginning of month m; otherwise zeroj= Equivalent monthly growth rater= Nominal annual return as a decimaln= Compounding periods per yearR = (FV - T) / (1 + i)^t
Use this when tax and inflation adjustments are enabled.
R= Real after-tax valueFV= Future value before tax and inflation adjustmentT= Estimated tax on gainsi= Inflation rate as a decimalt= Time in years$5,000 initially plus $250 monthly for 30 years at 7%
Calculate total contributed principal
$5,000 + ($250 x 360) = $95,000
Apply beginning-of-month contributions and monthly growth
Estimated growth = $252,354.36
Add principal and growth
$95,000 + $252,354.36 = $347,354.36 nominal value
$10,000 for 20 years at 7%, with 15% tax and 3% inflation
Calculate annual compound growth
$10,000 x (1 + 0.07)^20 = $38,696.84 nominal value
Apply tax to positive gains at the horizon
($38,696.84 - $10,000) x 15% = $4,304.53 tax
Adjust the after-tax balance for inflation
$34,392.32 / (1 + 0.03)^20 = $19,042.19
Investment guide
An investment calculator estimates future value from a starting amount, recurring contributions, expected annual return, and time. It shows how monthly investing can build principal while compound growth adds estimated gains.
The result is a scenario, not a forecast or guaranteed return. It assumes one constant return and does not simulate market volatility.
These examples use the same calculation engine as the interactive calculator. Values are rounded to cents for display.
$5,000 starting balance, $250 contributed monthly at the beginning of each month, 7% nominal annual return, monthly compounding, and 30 years.
$10,000 starting balance, no recurring contributions, 7% nominal annual return, annual compounding, 20 years, 15% tax on positive gains, and 3% annual inflation.
Recurring contributions are added at the beginning of each selected contribution period. A monthly contribution enters before that month's growth; quarterly and annual contributions enter before growth in their scheduled starting month. Beginning-period contributions therefore receive slightly more modeled growth than equal end-period contributions.
The annual-return input is a nominal constant assumption. The calculator converts yearly, quarterly, monthly, or daily compounding to an equivalent monthly rate for its month-by-month projection. More frequent compounding can increase the modeled balance when the nominal return is positive, but real investment returns do not arrive evenly.
When enabled, tax equals one constant rate multiplied by positive nominal gains at the end of the horizon. Contributions are not taxed. This differs from the interest calculator's yearly tax deduction and does not represent a particular taxable, tax-deferred, or tax-free account.
Compare fixed simple and compound interest →Nominal value is the projected future-dollar balance. Inflation-adjusted value divides the after-tax balance, or nominal balance when tax is disabled, by a constant compounded inflation factor. It estimates purchasing power; it is not another account balance or an inflation forecast.
Compare historical U.S. dollar purchasing power →The model excludes fees, changing returns, market volatility, sequence-of-returns risk, contribution changes, withdrawals, dividends taxed during the projection, and account-specific rules. Actual investments can lose value, including principal.
It estimates a future balance from a starting amount, regular contributions, time, and an assumed annual return.
Monthly investments add to principal at the beginning of each month in this calculator. Each contribution then receives estimated growth for that month and the remaining projection.
Not exactly. Compound interest usually describes a fixed rate applied to principal. Investment return is an assumption that can change and may include market gains or losses.
Use them only when you want simplified after-tax and purchasing-power estimates. Leave both disabled for a nominal projection.
Contributions are added at the beginning of each selected monthly, quarterly, or annual contribution period, before that month's estimated growth.
No. It is a constant planning assumption. Actual investments can rise or fall, and results can differ because of volatility, fees, taxes, contribution timing, and account rules.
It applies one selected tax rate to positive nominal gains at the end of the projection. It does not tax contributions and does not model annual realization, dividends, account types, tax brackets, deductions, or changing laws.
Nominal value is the projected future-dollar balance. Inflation-adjusted value divides the after-tax or nominal balance by a constant compounded inflation factor to estimate purchasing power in today's dollars.
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