Investment Calculator
Find the end balance, or the deposit, return or time needed to reach a goal.
How to use Investment Calculator
- Choose what to calculate: the end balance, or the deposit, return or time needed for a target.
- Fill in the other values.
- Read the answer, the split between what you paid in and growth, and the year-by-year table.
How it works
Growth is compounded monthly from the yearly return you enter, treated as an effective annual rate: the monthly rate is i = (1 + return)^(1/12) − 1, and deposits are added at the end of each month. The end balance is FV = start × (1 + i)ⁿ + deposit × ((1 + i)ⁿ − 1) ÷ i for n months.
To solve for the monthly deposit, that formula is rearranged. The return needed has no closed form, so it is found by bisection to many decimal places. The time needed is counted month by month until the balance reaches the target.
If you enter inflation, the end balance is also shown in today’s money: FV ÷ (1 + inflation)^years.
Example
10,000 to start plus 500 a month at 7% for 20 years: you pay in 130,000 and end with about 292,465, of which about 162,465 is growth. To reach 500,000 instead, the same plan needs about 909 a month.
Frequently asked questions
How is this different from the compound interest calculator?
This one works backwards from a goal: it can tell you the deposit, the return or the time needed to reach a target. The compound interest calculator focuses on compounding frequency and deposit timing.
What return should I enter?
Use your own assumption. Broad share indexes have returned very roughly 7–10% a year before inflation over long periods, with large swings; savings accounts and bonds return less. Past returns do not predict future ones.
Does it account for inflation?
Enter an inflation rate to see the end balance in today’s money as well.
Are fees and taxes included?
No. Subtract yearly fees from the return you enter (for example 7% return with a 0.5% fee is 6.5%).
Limitations
- A constant return every year; real investments fluctuate and can lose money.
- Fees and taxes are not modelled.
- For information only. It is not financial advice and not an offer of credit.
Last reviewed November 9, 2026. How we build and test tools.