How to Calculate Sinking Fund
What is Sinking Fund?
A sinking fund is a dedicated savings account for a planned future expense. Instead of borrowing when the expense arrives, you save a fixed amount each month in advance — eliminating debt and interest.
Formula
monthly_contribution = future_goal / months; or FV = payment × [((1 + r)^n - 1) / r]
- goal
- Future goal ($) — Amount you want to save
- months
- Time horizon (months) — Months until goal date
- rate
- Interest rate (%) — Annual rate on sinking fund (optional)
- payment
- Monthly payment ($) — Amount to set aside each month
Step-by-Step Guide
- 1Monthly Saving = (Goal − Already Saved) ÷ Months Remaining
- 2Common sinking funds: car replacement, holiday, home repairs, Christmas
- 3Separate accounts for each fund prevent accidental spending
- 4High-interest savings accounts maximise growth
Worked Examples
Input
$3,000 holiday in 6 months
Result
Save $500/month
Input
$10,000 car deposit in 2 years
Result
Save $416.67/month
Input
$1,200 Christmas fund, 10 months
Result
Save $120/month
Frequently Asked Questions
What is a sinking fund?
Regularly saving towards a large future expense (car, home repair, vacation). Unlike an emergency fund, this is for planned spending.
Should I earn interest on a sinking fund?
Yes! Even 4–5% in a high-yield savings account helps. Formula adjusts for compounding interest.
What are common sinking funds?
Car maintenance/replacement, home repairs, insurance deductibles, vacation, wedding, annual subscriptions.
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