Sinking Fund Calculator
Break big, irregular bills into a steady monthly set-aside so car insurance, property tax, holidays, and repair funds never hit as surprises.
Build your sinking funds
Add each irregular expense, how much you need, when you need it, and anything already saved. The calculator shows what to set aside every month for each fund and the full household total.
Add a sinking fund
$0 / month
Add your irregular expenses to see your total monthly set-aside.
How to use this calculator
Enter a fund name, the dollar amount you will need (the target), how many months until you need it, and any amount you already have saved toward it. Press Add Fund. The tool calculates the monthly contribution needed for each fund and a grand total so you can build one clean line item into your budget. Add as many funds as you need. Remove any fund with the × button. Use the sample set button to preload a typical household example.
What belongs in a sinking fund
- Predictable annual bills: car insurance, homeowner or renter insurance, property tax, HOA dues, vehicle registration, annual software subscriptions, professional memberships.
- Seasonal spending: holiday gifts, back-to-school, birthdays, summer camps, winter heating prepay, spring landscaping.
- Planned maintenance: HVAC service, tire replacement (every 40-60k miles), timing belt at 100k miles, septic pumping, gutter cleaning, roof inspection.
- Known future purchases: next car down payment, laptop replacement on a 4-year cycle, appliance replacement reserves, vacation fund.
- Pet care: annual vet exams, teeth cleaning, medication refills, boarding during travel.
Sinking fund vs emergency fund
- Sinking fund: Known bill, known approximate date. You save a fixed amount monthly so the money is ready when due.
- Emergency fund: Unknown event, unknown date. Typically 3-6 months of essential expenses held in a separate account you do not touch.
- Why both matter: Without sinking funds, every car registration or holiday season becomes an emergency. Separating them means your real emergency fund stays intact for real emergencies.
FAQ
How many sinking funds should I have?
Most households do well with 5 to 10 funds. Fewer than 5 and you lose the benefit of planning out individual bills. More than 10 and the tracking overhead starts to outweigh the value. Start with the three or four most painful irregular bills, then add more as the habit takes hold.
Where should I keep sinking fund money?
A high-yield savings account at an online bank is the best choice for most households. Look for accounts that support sub-accounts or "buckets" (Ally, Capital One 360, SoFi, and Discover all offer this). You earn interest, the money is still liquid, and each fund stays visually separate without needing multiple logins.
What if I cannot afford all the funds at once?
Prioritize by due date and penalty risk. Fund anything due in the next 3 months first, anything with late fees or interest second, and everything else after that. You can always stretch a target over more months or reduce it (smaller holiday budget, delay the laptop replacement by six months). Partial funding still prevents the all-or-nothing shock of a surprise bill.
How is this different from just budgeting monthly?
A monthly budget handles recurring expenses like rent and groceries. Irregular expenses break a monthly-only budget because they show up in lumps. Sinking funds smooth the lumps by converting each annual or quarterly bill into a monthly equivalent that your budget can actually absorb.
What happens if my target changes mid-year?
Update the target in your records and recalculate. If insurance went up $200, divide the new shortfall by the months remaining and add that to your monthly contribution. The calculator already accounts for "already saved" so you can recompute a fresh monthly number after any change without starting over.
Can I use one sinking fund account for everything?
Yes, as long as you keep a separate record (spreadsheet, notebook, or an account with named buckets) of what each dollar is for. The risk with a single undifferentiated account is spending property-tax money on holiday gifts because it all looks like one pile. The ledger is the discipline, not the account itself.