Free tool
How much do you need to save each month?
Enter a target, a deadline and an expected annual return. The deposit is solved backwards from the future value, not guessed.
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The formula behind the number
The calculator treats your current savings as a lump sum that compounds monthly, and the deposit as an ordinary annuity with payments at the end of each month. The monthly rate is the annual return divided by 12, and the deposit is solved from the future-value identity rather than by trial and error.
The result is the amount that lands exactly on the target, so rounding up is always safer. A higher assumed return lowers the deposit, which is why the assumed rate should be a conservative one for the account you actually use.
What it leaves out
Tax on interest, account fees, inflation and irregular deposits are not modelled. If the money sits in a taxed account, enter a return net of tax. If you expect bonuses or windfalls, subtract them from the target first and run the calculation on the remainder.
Frequently asked questions
Does the deposit go in at the start or end of each month?
The end. That is the conservative assumption: a deposit made at the start of the month would earn one extra month of interest and need to be slightly smaller.
What should I use as the annual return?
The rate you can defend for the account holding the money, after fees and tax. A high-yield savings account and an index fund do not deserve the same assumption.
Why is the interest amount sometimes zero?
If your current balance already grows past the target on its own, no deposit is required and the interest line is clipped at zero rather than showing a negative number.
Can I use it for a house deposit or a car?
Yes. Any goal with a fixed target and a deadline works; the currency is whatever you type.