Budgeting & Income
Sinking Fund Calculator
Most budget blow-ups are not emergencies. Car insurance, the holidays and a roof you already know is aging all have dates. A sinking fund gives each one a monthly amount, so a $1,400 bill in June is really $200 a month you have already set aside.
Tested against worked examplesHow we verify
What is left after regular bills and other saving.
e.g. annual car insurance premium.
e.g. the holidays.
e.g. a roof replacement you can see coming.
Set aside each month: $590
Set aside each month
$590
Across 3 goals — 9.8% of income.
Keep sinking funds in a separate high-yield savings account, not your checking account — money that shares an account with spending tends to get spent. Many banks let you open named sub-accounts for exactly this.
- Total you are saving toward
- $15,400
- Already set aside
- $2,200
- Available each month
- $600
- Left over after funding all goals
- $10
Each goal as a monthly figure
| Goal | Target | Saved | Months away | Monthly |
|---|---|---|---|---|
| Goal 1 | $1,400 | $200 | 6 | $200 |
| Goal 2 | $2,000 | $0 | 11 | $182 |
| Goal 3 | $12,000 | $2,000 | 48 | $208 |
Compare scenariosTry three values of one input
| Monthly income | |||
|---|---|---|---|
| Set aside each month | $590 | $590 | $590 |
| Total you are saving toward | $15,400 | $15,400 | $15,400 |
| Already set aside | $2,200 | $2,200 | $2,200 |
| Available each month | $600 | $600 | $600 |
| Left over after funding all goals | $10 | $10 | $10 |
Every other input stays at the value you set above — currently $6,000 for monthly income. Differences are measured against the first column.
Saved scenariosSave this calculation
Saved in this browser only — no account, and nothing is sent to us. Clearing your browser data deletes them.
How this calculator works
Each goal's monthly figure is its remaining amount — target less what you have already saved — divided by the months until it is due. The totals sum across goals, and the surplus is what you have available each month minus that total. The share of income expresses the whole commitment against your monthly income.
No investment return is assumed — sinking funds are short-horizon and belong in cash, where the return is negligible and not worth the risk. Goals with a target of zero are ignored. The calculator does not prioritise for you when goals are unaffordable together; that decision depends on which expenses are essential and which can wait.
What this assumes
- The cost and the date you enter, divided evenly across the months between. No return is assumed on the balance unless entered.
- It assumes the cost is known. Where it is a guess, round up rather than down.
- It is separate from an emergency fund by design — expected-but-irregular costs should not compete with genuine emergencies.
What changes this number
- Months available
- The whole mechanism. Starting earlier reduces the monthly amount proportionally.
- Accuracy of the target
- Underestimating turns a planned cost back into an emergency.
- Number of funds
- Several small ones running in parallel is what makes a budget stop being ambushed.
A worked example
Take the insurance, holidays and a roof scenario. These figures are produced by the calculator above, not written alongside it, so they always match what the tool returns.
What you enter
- Goal 1 — target
- $1,400
- Goal 1 — months away
- 6 months
- Goal 2 — target
- $2,000
- Goal 2 — months away
- 11 months
- Goal 3 — target
- $12,000
- Goal 3 — months away
- 48 months
What it returns
- Set aside each month
- $590
- Total you are saving toward
- $15,400
- Already set aside
- $2,200
- Available each month
- $600
- Left over after funding all goals
- $10
Keep sinking funds in a separate high-yield savings account, not your checking account — money that shares an account with spending tends to get spent. Many banks let you open named sub-accounts for exactly this.
Try an example
Frequently asked questions
What is a sinking fund?
A pot of money you build gradually toward a known future expense. Instead of being surprised by a $1,200 insurance bill, you save $100 a month for a year and pay it from the fund. The term comes from corporate finance, where companies set aside money to retire a bond at maturity.
How is a sinking fund different from an emergency fund?
An emergency fund covers the unexpected — a job loss, a medical bill, a car that dies without warning. A sinking fund covers the expected-but-irregular: premiums, registration, the holidays, a replacement you can see coming. Keeping them separate stops planned spending from draining your safety net.
What should I have a sinking fund for?
Anything large and irregular that you can anticipate: insurance premiums, property tax, car maintenance and registration, the holidays, annual subscriptions, a known home repair, next year's vacation. If it recurs or you can see it coming, it belongs in a sinking fund rather than in a month it happens to land in.
Where should I keep the money?
In a high-yield savings account separate from your checking, ideally in named sub-accounts so each goal is visible. Physical separation matters more than the interest — money mingled with everyday spending gets spent, and the whole point is that this money is already accounted for.
What if I cannot afford all my sinking funds?
That is useful information, not a failure. It means your known future expenses exceed what your budget can absorb, which would have become a crisis later regardless. Stretch the deadlines you can, lower the targets you can, and fund the nearest and most essential goals first.
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Disclaimer: DayCents provides this calculator for educational purposes only. Results are estimates based on your inputs and the stated assumptions — they are not financial advice, a quote, or an offer of credit. Consult a qualified financial professional before making major money decisions.