Working Capital Needs Calculator
Estimate the cash your business must tie up in its operating cycle — inventory and receivables, less what suppliers finance through payables.
A worked example
Running this tool on current national benchmarks (Federal Reserve / Freddie Mac via FRED (St. Louis Fed)) — swap in your own numbers to see how the result moves.
- Annual operating costs (COGS)
- $600,000
- Days inventory held
- 45
- Days to collect receivables
- 40
- Days to pay suppliers
- 30
to fund a 55-day cash conversion cycle
- Cash conversion cycle55 days
- Tied up in inventory$73,973
- Tied up in receivables$65,753
How the working capital needed changes with annual operating costs (COGS)
Holding the other inputs at the example above, here is how the result moves as annual operating costs (COGS) changes.
| Annual operating costs (COGS) | Working capital needed | Cash conversion cycle |
|---|---|---|
| $300,000 | $45,205 | 55 days |
| $600,000 | $90,411 | 55 days |
| $1,200,000 | $180,822 | 55 days |
| $2,400,000 | $361,644 | 55 days |
The math behind it
The calculator first finds your cash conversion cycle: days inventory held plus days to collect receivables minus days you take to pay suppliers. That is how many days cash is tied up between paying for inputs and collecting from customers. It multiplies that day count by your daily operating cost — annual operating costs divided by 365 — to estimate the working capital you must fund. It also breaks the cycle into the cash sitting in inventory, in receivables, and the portion financed by payables.
Assumptions & limits
- Costs are spread evenly across the year at annual operating costs divided by 365; seasonal swings are not modeled.
- The cash conversion cycle can be negative if suppliers finance you faster than you carry inventory and receivables — meaning suppliers effectively fund your operations.
- Working capital need is driven by cost of goods, not revenue, so it reflects what you must lay out rather than what you sell for.
- It estimates ongoing operating-cycle funding; it does not size a cash buffer for emergencies or one-time capital needs.
Common questions
What is the cash conversion cycle?
It is the number of days between paying for inventory and collecting the cash from selling it, adjusted for how long you take to pay suppliers. The formula is days inventory plus days receivable minus days payable. A shorter cycle means cash comes back faster; a longer one means more of your money is tied up funding operations at any moment.
Can working capital needs be negative?
Yes. If you collect from customers and turn inventory faster than you pay suppliers, your cash conversion cycle goes negative — suppliers are effectively financing your business. Some large retailers run this way, using supplier credit as a source of free working capital rather than tying up their own cash.
How do I reduce how much working capital I need?
Shorten your cash conversion cycle with any of three levers: collect receivables faster (tighter terms, quicker invoicing), hold leaner inventory (better forecasting, just-in-time stocking), or negotiate longer terms to pay suppliers. Each shrinks the number of days your cash is tied up, freeing capital without borrowing.