How this calculator works
A sinking fund makes equal deposits to meet a future obligation. Interest and deposits occur at the same frequency, and the first deposit is at the end of the first interval. The rate solver permits non-negative interest. The time solver rounds up to a whole deposit period, so the accumulated value may slightly exceed the requested goal.
Formula
Future fund = payment x [(1 + i)^n - 1]/i. Sinking-fund factor = i/[(1 + i)^n - 1]. At i = 0, contribution = target/n.
Worked example
Two annual end deposits of $100 at 10% accumulate to $210. A $1,200 target over 12 months at 0% needs $100 monthly.
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Frequently asked questions
Is this a loan repayment?
No. Money is accumulated in a separate fund; no loan principal is reduced by these deposits.
When are deposits made?
At the end of each compounding interval. Beginning deposits would earn one additional interval of interest.
Why does the time answer exceed my goal?
The term is rounded up to the next scheduled contribution period.