Finance & Money
Sinking Fund Calculator
Compound the current balance and immediate addition through the exact deadline, then solve the end-of-month deposit required to fill the remaining future need.
Balance after immediate addition-
Monthly savings rate-
Future value of starting balance-
Future target not covered by starting balance-
Required end-of-month deposit-
Total planned recurring deposits-
Target less entered principal contributions-
Decision view
Sinking-fund path to the expense date
Sinking-fund path to the expense dateExisting cash, monthly deposits, and modeled interest build to the future target.
Exact scenario comparisonMonths until expense changes while all other entered assumptions remain constant.
| Months until expense | Balance after immediate addition | Monthly savings rate | Future value of starting balance | Future target not covered by starting balance | Required end-of-month deposit | Total planned recurring deposits | Target less entered principal contributions |
|---|
Period-by-period detail
Sinking-fund contribution schedule
How to use Sinking Fund Calculator
- Define one expense and one due date.
- Enter only cash already dedicated to that expense.
- Automate the calculated monthly transfer and review the target when pricing changes.
Calculator guide
Understanding Sinking Fund Calculator
A sinking fund converts a known future bill into a recurring savings requirement while giving existing dedicated cash time to earn interest.
Calculation method
How the calculation works
Compound the existing sinking-fund balance and solve the recurring end-of-month deposit needed to reach a known future expense. Add current and immediate cash, calculate its future value at the entered APY, and solve the ordinary-annuity payment that reaches the target after the entered months.
Expense calendar
Turn irregular bills into steady monthly cash flow
A dedicated sinking fund removes timing shocks from a regular budget.
Worked situations
Practical examples
- Annual insurance, equipment replacement, tuition, and property tax can each use a separate sinking fund.
- A shorter deadline raises the required monthly deposit.
- Existing cash reduces recurring need and earns modeled interest.
Better inputs
Useful tips
- Keep sinking funds separate from emergency reserves.
- Round the transfer upward for margin.
- Update the target from current quotes.
Before relying on the result
Limitations and common mistakes
- The target, rate, and deposit schedule are assumed stable.
- No withdrawals, fees, taxes, or missed deposits are modeled.
- Deposits occur at month end.
Reference
Key terms
- Sinking fund
- Cash accumulated gradually for a known future expense.
- Future target
- Amount required at the selected deadline.
- Immediate addition
- One-time cash added before recurring deposits begin.
- Required monthly deposit
- Solved end-of-month transfer under the entered assumptions.
Important note
Calculated from the entered values and stated financial terms. It is not a product quote, lending decision, tax filing, or investment recommendation.
Frequently asked questions
How is this different from an emergency fund?
A sinking fund is for a known expense with an expected date.
When are deposits assumed?
At the end of each month.
What if current cash already covers the future target?
The required monthly deposit can fall to zero.
Should the calculated amount be rounded?
Rounding upward can provide practical margin.