Sinking Fund Factor Calculator

Work out sinking fund factor instantly with clear inputs, formula shown and shareable results.

About Sinking Fund Factor Calculator

A sinking fund sets aside a level annual amount so that a known sum is available on a future date — typically to redeem a bond or replace an asset. The sinking fund factor is the deposit needed per unit of target.

Formula

Sinking fund factor

A/F = r / ((1+r)^n - 1)

r: Rate per year
n: Years

Worked example

With the default values below, Sinking Fund Factor Calculator returns Sinking Fund Factor (A/F) of 0.07586796. Change any input above and every figure here is recalculated in your browser.

Inputs used

Target Amountminimum 0: 500,000
Rate Per Yearaccepts 0–100 %: 6 %
Years To Accumulateaccepts 1–60: 10

Results

Sinking Fund Factor (A/F): 0.07586796
Annual Deposit Required: $37,933.98
Total Deposited: $379,339.79
Interest Contributed By The Fund: $120,660.21

Step by step

1Values used
2Sinking fund factor
3Sinking Fund Factor (A/F)= 0.07586796
4Annual Deposit Required= 37,933.98
5Total Deposited= 379,339.79
6Interest Contributed By The Fund= 120,660.21

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or fees or charges into account.
Figures are rounded for display to 8 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How does it relate to the amortisation factor?

They differ by exactly r: A/P = A/F + r, because a loan payment also has to service interest on the outstanding balance.

Does interest do much of the work?

Over long horizons yes — at 6% over 20 years roughly half the target comes from interest rather than deposits.