Reverse Compound Interest Calculator
Start from a target and work backwards. Find the return, the time or the monthly deposit you need to hit it.
Most calculators ask what you have and tell you what you will get. This one starts with the goal.
Choose what to solve for. The calculator finds the missing piece.
How it works
Solving for the rate uses a search to find the return that lands exactly on the target. Solving for years counts months until the balance crosses it.
Solving for the deposit uses the standard annuity formula. Returns compound monthly throughout.
The formula
i = monthly rate, n = months.
Tips
- If the required return looks above 10%, the plan needs more time or more money. Do not count on luck.
- Small changes in time matter more than small changes in rate.
Frequently asked questions
Is a required return of 12% realistic?
Not reliably. Long run stock returns have averaged around 10% before inflation, with big swings.
Why does solving for years give a whole number of months?
The calculator steps month by month and stops when the target is passed.
This is not financial advice. Nothing on this site is investment, tax, legal or financial advice of any kind.
The calculators give simplified estimates from the numbers you enter. They ignore taxes, fees, rate changes and real market returns, and they can be wrong.
Do not make financial decisions based on these results. Speak to a licensed financial adviser, accountant or lender before acting, and read the full disclaimer.