Hong Life CalculatorsUnderstanding the working capital requirement calculator — concept and principle
Every business that sells on credit and holds stock has money tied up in its operating cycle: customers have not paid yet, goods sit in the warehouse, and only part of this is financed by suppliers who let you pay later. This calculator estimates that net working capital requirement from your annual revenue, cost of goods sold (COGS) and three "days" ratios. Owners and finance teams use it to size a credit line, plan growth and see how faster collections or leaner inventory free up cash. It works with any currency.
How it is calculated
- Receivables = annual revenue × DSO ÷ 365
- Inventory = annual COGS × DIO ÷ 365
- Payables = annual COGS × DPO ÷ 365
- Net working capital needed = receivables + inventory − payables
DSO (days sales outstanding) is how long customers take to pay, DIO (days inventory outstanding) how long goods stay in stock, DPO (days payables outstanding) how long you take to pay suppliers.
The principle
Each balance is a flow multiplied by the time it waits. If you sell 2,000,000 a year, that is about 5,479 a day; if customers pay after 45 days, about 45 days of sales are always outstanding. Inventory and payables are measured at cost, so they use COGS rather than revenue. Supplier credit is a free source of funding, which is why payables are subtracted. The related cash conversion cycle is DSO + DIO − DPO, here 65 days.
Worked example
- Receivables = 2,000,000 × 45 ÷ 365 = $246,575.34.
- Inventory = 1,200,000 × 60 ÷ 365 = $197,260.27.
- Payables = 1,200,000 × 40 ÷ 365 = $131,506.85.
- Net working capital = 246,575.34 + 197,260.27 − 131,506.85 = $312,328.77.
How to read the result
This is the amount of cash the operating cycle absorbs at the current scale. It grows roughly in proportion to sales, so a fast-growing company can run short of cash even while profitable. Each day of DSO here is worth about 5,479 in cash, and each day of DIO or DPO about 3,288. Compare your days ratios with your own history and with peers in the same industry, since normal values differ greatly between, say, retail and engineering.
Common mistakes
- Using revenue instead of COGS for inventory and payables.
- Taking year-end balances in a seasonal business, which can be far from the average.
- Mixing 360-day and 365-day conventions when comparing reports.
- Forgetting other items such as prepayments, accrued wages or taxes payable.
Frequently asked questions
Is negative working capital bad?
Not necessarily. Some retailers collect cash at the till and pay suppliers later, so suppliers finance the business. It becomes risky if it reflects an inability to pay.
How do I find DSO from my accounts?
DSO = average trade receivables ÷ annual credit sales × 365.
Why does growth need cash?
Higher sales raise receivables and inventory before customers pay, so cash goes out ahead of cash coming in.
Sources: Brealey, Myers & Allen, Principles of Corporate Finance (McGraw-Hill), chapter on working capital management · Ross, Westerfield & Jaffe, Corporate Finance (McGraw-Hill)