Calculate Your Sinking Fund Per Paycheck
A sinking fund turns a large future expense into a small regular one. Enter the amount, the date you need it and what you have saved so far, and the calculator counts the paychecks that arrive in time and works out exactly what each one has to carry.
Sinking fund calculator
Enter what you need, when you need it, and what you have already put aside. Everything updates as you type, and nothing is sent anywhere.
- Still to save
- $660.00
- Paychecks before it is due
- 13
- Set aside per paycheck
- $50.77
- Final contribution
- $50.76
The amount does not divide evenly, so the spare cents sit on the earliest paychecks and the last one is $50.76. The contributions add up to $660.00 exactly, which is the point: a plan that lands a few cents short is a plan that failed.
Funding schedule
The figures it starts with are an example. Change them to your own.
How it counts
Remaining is the total you need minus what you have already put aside. If that is zero or less, the goal is funded and nothing more needs to come out of a paycheck.
Eligible paychecks are the paydays that arrive strictly before the due date. A paycheck landing on the due date itself does not count: the money needs to be in place when the expense is paid, and relying on a deposit that arrives the same morning is not a plan. If that is genuinely how your timing works, set the due date one day later and the calculator will include it.
Per paycheck is the remaining amount split across those paychecks. Because money comes in whole cents and most amounts do not divide evenly, the spare cents sit on the earliest contributions and the final one is a few cents smaller. The contributions add up to the remaining total exactly, which matters: a plan that lands six cents short of a $480 insurance bill is a plan that failed.
What a sinking fund is
It is money set aside on purpose, on a schedule, for a specific expense you already know is coming. Car insurance in March. Registration in July. The holidays in December. A vet visit you know is annual.
The expense is not a surprise. Only its size is a problem, and only because it arrives all at once against a budget built around a paycheck. Splitting it across the paychecks that arrive before it removes the lump without changing the total.
How it differs from an emergency fund
They are often confused and they do opposite jobs.
An emergency fund is for things you cannot predict: a job loss, a burst pipe, an urgent repair. It is one pool, it has no target date, and the goal is never to spend it.
A sinking fund is for something you can predict exactly. It has a name, an amount and a date, and spending it is the point. When the insurance bill arrives, the fund empties and starts again.
Keeping them separate is what stops an expected expense quietly consuming the money set aside for a genuine emergency.
What belongs in one
Anything that is known, large relative to one paycheck, and not monthly:
- Insurance premiums paid every six or twelve months
- Vehicle registration, inspection, tires, scheduled servicing
- Annual subscriptions and professional memberships
- Property tax or an HOA charge not folded into a mortgage payment
- The holidays, birthdays, an annual trip
- Predictable medical and dental costs, including a deductible that resets each year
Why monthly saving advice does not fit biweekly pay
Most guidance on this says to divide the amount by the number of months. That works if you are paid monthly and nobody else is.
On a biweekly schedule you are paid 26 times a year, not 24, so a monthly figure is either slightly too much or slightly too little every single time, and the error compounds over a year. You also do not get paid on the first of the month, which is when a monthly plan implicitly assumes you set the money aside.
Counting actual paydays removes both problems. The calculator counts the paychecks that genuinely arrive before the date and divides across those, which is why it asks for your pay frequency and your next payday rather than a number of months.
Starting late
If the expense is near and the fund is not there, the per-paycheck figure will be uncomfortable. That number is still the useful one, because it is the truth about what the schedule requires.
Three things to do with it:
- Fund what you can and name the gap. Knowing you will be $200 short in six weeks is a solvable problem. Discovering it on the day is not.
- Look for a nearer source. A three-paycheck month inside the window is the easiest way to close a gap without touching normal spending.
- Start the next cycle immediately. The day an annual bill is paid is the best day to start saving for the next one, because you get the full twelve months instead of the four you had this time.
If no paycheck arrives before the due date, the calculator says so plainly rather than producing a figure. That is the case the fund exists to prevent, and the answer is the last item above.
When the target or the date changes
An amount estimated in January is often wrong by March, because premiums rise and quotes change. Update the target and the calculator redistributes what is left across the paychecks still ahead of you. The contributions you have already made stay counted as saved, so a raised target increases the remaining per-paycheck figure rather than restarting the plan.
If the date moves closer, the same thing happens with fewer paychecks. If it moves further out, the per-paycheck figure drops.
How Pocket Runway handles it
In the app a sinking fund is not a note to yourself. Its per-paycheck contribution is reserved inside each pay period, so it comes off the money available before the daily spending number is calculated, the same way a bill does. Money you actually move into a savings goal is recorded as a transfer, so it satisfies that period's reserve rather than being charged twice.
The result is that the amount set aside for next March's insurance is never part of what is safe to spend this week, and the forward forecast shows each future pay period with its contributions already accounted for. How safe to spend is calculated covers where those reserves sit in the arithmetic.
Get started with Pocket Runway
A calculator gives you the figure once. The app keeps it reserved every pay period, adjusts it when the target or the date changes, and stops it being spent by accident, which is the part a one-time calculation cannot do.
Sinking fund questions
What expenses belong in a sinking fund?
Anything predictable, not monthly, and large enough relative to a paycheck that paying it in one go hurts: insurance renewals, registration and vehicle maintenance, annual subscriptions, property tax, the holidays, an annual deductible, a planned trip.
Should I keep sinking funds in separate bank accounts?
Separate from your spending account, yes. Separate from each other is optional. One savings account holding several funds works as long as you track how much of it belongs to each, which is what the app does for you. What matters is that the money is not sitting in checking, where it looks like spending money.
What happens if I miss a contribution?
Update what you have actually saved and the calculator redistributes the remainder across the paychecks left. Missing one makes the rest slightly larger. Missing several near the end is the situation worth avoiding, which is why front-loading is safer than back-loading.
How is a sinking fund different from a savings goal?
Mostly in whether there is a deadline. A sinking fund has a date and an amount attached to a specific expense, and spending it is the plan. A savings goal is often open-ended: a house deposit, a bigger emergency fund. The arithmetic is the same; the difference is whether a date forces the per-paycheck figure.
Can I fund something unevenly across paychecks?
Yes, and there are good reasons to. If a three-paycheck month falls inside the window, putting more on the extra check and less on the others is sensible. The calculator gives you the even split as a baseline; anything you front-load simply leaves less for the paychecks after it.
This calculator is general educational information, not financial advice. It works only from the figures you enter, and does not account for interest earned, fees, inflation, or a change in the expense itself. All example figures are illustrative. It runs entirely in your browser: nothing you type is sent anywhere, stored, or added to a Pocket Runway account.
Related reading: which paycheck should cover each bill, find your three-paycheck months, budgeting with irregular income, the daily spending allowance calculator, or the full guide library.