Formula
Current savings grow first. The monthly deposit fills the rest:
Payment = (goal − grown savings) × r / ((1 + r)^n − 1)
r is the monthly rate and n is the number of months. If current savings already grow past the goal, the payment is zero.
Assumptions
- The return stays constant.
- Deposits are made at the end of every month.
Worked example
Reaching $500,000 in 20 years from $50,000 already saved, at 7%, takes $572.18 a month.
Input definitions
- Already saved
- Money that keeps growing while you add the monthly amount. Zero is allowed.
Limitations
This is an estimate, not a loan offer, tax filing, or investment advice. The currency control changes the symbol only.
Questions
What if I am already on track?
The monthly savings figure is zero when today's balance can grow to the goal alone.
Is the return guaranteed?
No. It is the rate you type.