Investment Goal Calculator
Most investors start with a target: a down payment fund, a retirement portfolio, or a future account value that would change their choices. This calculator reverses the usual compound-interest question. Enter the target, what you already have, the years available, and the return assumption to estimate the monthly investment needed to close the gap.
Required monthly investment
$1,153
10 years
Future gap to fund
$199,517
Total new contributions: $138,325
Current portfolio at target date
$100,483
Current progress
$300,000
Assumes monthly compounding and contributions made at the end of each month. Figures are nominal and ignore taxes, fees, inflation, and market volatility.
Reverse the compound-interest question
A normal compound-interest calculator asks what today's contributions might become. A goal calculator asks the opposite question: given a future target, how much new money must be added each month? The current portfolio is grown forward first, then the remaining gap is divided by the future value of a monthly contribution stream.
How to set the target
Use a target that is tied to a real planning decision rather than a round number. For a house fund that might be the cash needed by a certain year. For long-term investing it might be the portfolio value needed before withdrawals, lower work hours, or a business transition. Then rerun the calculator with lower return assumptions to see how sensitive the monthly number is.
What the number does not guarantee
The output is a funding estimate, not a forecast and not a recommendation to buy any asset. Markets do not deliver smooth annual returns, and taxes, fees, inflation, and sequence risk can all change the real result. Treat the monthly number as a planning target to pressure-test against your budget and risk capacity.
FAQ
Why is my required monthly investment zero?
That means the current portfolio, under your return and time assumptions, already reaches the target by the target date. Lower the return assumption or shorten the time horizon to test a more conservative case.
Should I use the same return assumption for every goal?
No. A shorter or safer goal usually deserves a lower return assumption because there is less time to recover from market losses. Long-term equity-heavy goals may justify a higher assumption, but it should still be stress-tested.
Does this calculator include taxes and inflation?
No. It uses nominal dollars and a constant-return assumption. Use the fee-drag, CAGR, and compound-interest tools to test adjacent assumptions before treating the monthly number as a budget target.
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