Sinking funds planner
Gifts in December, the car insurance in spring, a trip in summer: list the bills you can see coming and get one steady amount to set aside each month, so none of them lands all at once.
Expenses ahead
Set aside each month
$641.96
across 5 of 5 expenses, starting Oct 2026
- Total of the expenses
- $3,870.00
- Already saved
- $660.00
- Still to save
- $3,210.00
- Holiday gifts$225.00 a month
- Software & memberships$60.00 a month
- Car insurance (yearly)$126.00 a month
- Car service & tyres$64.29 a month
- Summer trip$166.67 a month
What you set aside each month
- Total set aside
Changes are saved in this browser as you go.
Educational use only — not financial advice
One small amount for each big bill
A sinking fund is money set aside bit by bit for a cost you know is coming. Instead of one large payment knocking the month off balance, the cost is spread over the months before it is due.
Each month = (amount − already saved) ÷ deposits left
Deposits are counted one a month, starting this month and ending the month before the due month; an expense due this month gets a single deposit, now. Amounts are rounded up to the cent so each fund is complete on time. When the saved figure reaches the amount, the fund is marked fully saved and drops out of the monthly total.
Example: $840 of car insurance due in five months, with $210 already put by, needs $630 more over five deposits: $126 a month. Add the other funds and the total at the top is the single transfer to make each month; the chart shows it shrinking as each bill comes due.
Good candidates are yearly insurance, car servicing, holidays, gifts, school costs and subscriptions you pay once a year. For surprises you cannot date, use the emergency fund calculator instead.
Questions
Do I need a separate account for each fund?
No. Many people keep all sinking funds in one place and track each fund's share on paper or in a planner like this one. Update the "saved" column as you go so the monthly amounts stay right.
What if an expense repeats every year?
Plan this year's occurrence. Once it is paid, change the due month to next year and the saved figure to zero, and the planner spreads it over the next twelve months.
Where is my list saved?
In this browser's local storage, under the key stableharvest-sinking, on this device only. "Clear all" removes it; the CSV download keeps a copy you can open in any spreadsheet.