Free sinking fund calculator
Find the exact deposit to hit any savings target. Enter your target amount, an interest rate, and the number of years, then pick monthly, quarterly, or annual deposits. The calculator returns the required periodic deposit, the total you contribute, and the interest your fund earns — updated live, as you type.
On this page15 sections
Estimates only, based on a constant deposit and rate. Not financial advice.
Results are estimates. Consult a professional.
What is a sinking fund?
A sinking fund is money you set aside on a regular schedule so that a known, future expense is fully funded by the time it arrives. Instead of scrambling for a large lump sum on the due date, you accumulate it in small, predictable deposits. The principle is identical whether the saver is a household putting away cash for a $30,000 car or a corporation retiring a $200 million bond: pick a target, pick a deadline, and let regular contributions — plus a little interest — close the gap. This sinking fund calculator returns the exact deposit you need the moment you enter your target, rate, and term.
The name comes from the corporate-bond world, where money is paid into a fund that gradually sinks (extinguishes) a debt. In personal finance the term has been adopted for goal-based saving — vacations, insurance premiums, holiday gifts, a new roof — any expense you can see coming. Both senses share one formula, and this page covers both.
Sinking fund formula
A sinking fund is the future value of an annuity, solved backwards. Rather than asking what a known deposit grows to, it asks what deposit reaches a known target. The required payment is the target divided by the annuity factor:
When the rate is zero the denominator collapses and the formula simplifies to PMT = FV ÷ n — you simply split the target evenly across the periods, because there is no interest to help. The calculator handles this edge case automatically, so a 0% rate never produces a divide-by-zero error.
How to use the sinking fund calculator
- Enter your target. The total you need to have saved by the deadline — the price of the purchase or the principal of the debt.
- Enter the annual interest rate. The yield on the account or investment holding the fund. Use 0% if you are saving in a non-interest account and want the straight-line answer.
- Enter the number of years. How long until the money is needed.
- Pick the deposit frequency. Monthly, quarterly, or annual. The calculator converts your annual rate and term to match.
- Read the required deposit. The result hero shows the fixed amount to set aside each period, with total deposited and interest earned beside it.
A worked example using the sinking fund calculator
Dana wants to pay cash for a $30,000 car in five years and will keep the money in a high-yield savings account earning 4% a year, paid monthly. How much does she need to set aside each month?
Step 1 — Convert the inputs to per-period terms
With monthly deposits, the periodic rate is 4% ÷ 12 = 0.3333% a month, and the number of periods is 5 years × 12 = 60. The target (future value) is $30,000.
Step 2 — Apply the sinking fund formula
Step 3 — Read the deposits vs. interest split
Sinking fund deposit schedule
A schedule shows how the balance climbs to the target as deposits and interest stack up. The table below uses a simpler version of the same goal — $30,000 in 5 years at 4%, deposited once a year — so each row is one full period. The annual deposit works out to $5,538.81, and the closing balance lands exactly on $30,000.
| Year | Opening balance | Interest earned | Deposit | Closing balance |
|---|---|---|---|---|
| 1 | $0.00 | $0.00 | $5,538.81 | $5,538.81 |
| 2 | $5,538.81 | $221.55 | $5,538.81 | $11,299.18 |
| 3 | $11,299.18 | $451.97 | $5,538.81 | $17,289.96 |
| 4 | $17,289.96 | $691.60 | $5,538.81 | $23,520.37 |
| 5 | $23,520.37 | $940.81 | $5,538.81 | $30,000.00 |
Each year's interest is earned on the opening balance; the deposit is added at period-end. Total deposited $27,694.07 + total interest $2,305.93 = $30,000 target.
Sinking fund vs. emergency fund
The two are easy to confuse but serve opposite jobs. A sinking fund is for the known — expenses you can see on the calendar and plan a deposit toward. An emergency fund is for the unknown — the surprise medical bill, the job loss, the blown transmission. You contribute to a sinking fund with a deadline and a target in mind; you build an emergency fund to a rough months-of-expenses cushion and then leave it alone until disaster strikes.
| Sinking fund | Emergency fund | |
|---|---|---|
| Purpose | A specific, planned expense | Unexpected, unplanned costs |
| Has a target date | Yes — a deadline drives the deposit | No — open-ended buffer |
| Typical size | The cost of one goal | 3–6 months of expenses |
| When you spend it | On the planned purchase | Only in a genuine emergency |
| After it is spent | Close it or start a new goal | Replenish back to target |
Most planners recommend keeping both: the sinking fund stops planned bills from raiding the emergency fund.
A sinking fund also differs from a plain savings goal only in framing — both solve for a deposit toward a target. The distinguishing feature of a sinking fund is the named purpose and the explicit deadline that sets the schedule.
Personal vs. corporate (bond) sinking funds
Personal sinking funds
For households, a sinking fund is a budgeting habit: open a separate account, name it for a goal — annual insurance, property taxes, holidays, a car, a wedding — and auto-transfer a fixed amount each payday. Spreading a $1,200 annual premium into $100 a month turns a lump-sum shock into a line item, and it keeps the emergency fund untouched for true emergencies.
Corporate bond sinking funds
In corporate finance, a sinking fund is a provision in a bond's indenture requiring the issuer to set aside money — often with a trustee — to retire the debt gradually rather than face the entire principal at maturity. The company makes periodic deposits and uses them to repurchase bonds on the open market or call them at a set price. This reduces default risk for bondholders, which in turn can lower the issuer's borrowing cost and improve its credit rating. The same PMT formula tells the treasurer how much to deposit each period to retire the issue on schedule.
| Personal sinking fund | Corporate (bond) sinking fund | |
|---|---|---|
| Who runs it | An individual or household | A bond issuer, often via a trustee |
| Goal | Fund a planned purchase | Retire bond principal before/at maturity |
| Held where | A savings or money-market account | A trustee-managed fund |
| Main benefit | Avoids debt and budgeting shocks | Lowers default and credit risk |
Different stakes, identical arithmetic — the sinking fund formula serves both.
Why use a sinking fund?
- Avoid debt. Funding a known expense in advance removes the need for a loan or credit card when the bill lands.
- Smooth your cash flow. Turning irregular large bills into level monthly deposits makes budgeting predictable.
- Earn interest along the way. Money parked in a yielding account works for you, shrinking the deposit you need to hit the target.
- Protect the emergency fund. Planned costs come from the sinking fund, leaving the emergency cushion intact for real surprises.
- For issuers, cheaper borrowing. A sinking-fund provision signals discipline, reduces default risk, and can win a better credit rating and lower coupon.
Tips for building a sinking fund
- One account, many goals — or one each. A single high-yield account with a spreadsheet tracking each goal works; so do separate named sub-accounts. Pick whichever you will actually maintain.
- Automate the deposit. Schedule the transfer for payday so the contribution happens before you can spend it.
- Round up. If the calculator says $452.50, deposit $460 — the buffer absorbs a missed month or a higher-than-expected price.
- Revisit when inputs change. A new estimate, an earlier deadline, or a rate change all shift the required deposit. Re-run the calculator and adjust.
- Keep it liquid for near-term goals. Money needed within a few years belongs in savings or a CD, not in volatile investments that could be down when you need it.
Sources and methodology
The calculator applies the standard sinking-fund (future-value-of-an-annuity-payment) formula, PMT = FV × r / ((1 + r)^n − 1), with deposits at the end of each period and the rate compounding at the deposit frequency. The 0% case uses the straight-line PMT = FV ÷ n. The definitions of personal and corporate (bond) sinking funds follow standard corporate-finance and personal-finance references.
Corporate Finance Institute — Sinking Fund (definition, examples, purpose).Sinking fund — Wikipedia (corporate-bond mechanism and methods of retirement).Frequently asked questions about the free sinking fund calculator
About this sinking fund calculator
This sinking fund calculator runs entirely in your browser. Every figure you enter stays on your device — nothing is sent to a server, logged, or shared. It applies the standard PMT = FV × r / ((1 + r)^n − 1) formula, converts your annual rate and term to the deposit frequency, and falls back to a straight-line target ÷ periods when the rate is 0%, updating instantly as you type.
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