Working Capital Calculator

What working capital actually measures

Working capital is the cash that needs to be circulating through the business at any given time to keep operations running. When you buy inventory, it sits on the shelf for a while before becoming a sale. When you make a sale on credit, it sits in AR for a while before becoming cash. Suppliers extend you credit too, partially offsetting that. The net amount floating in the cycle at any moment is working capital.

Most owners experience working capital as the constant tension between revenue (which looks healthy on the P&L) and cash (which can feel tight even in a profitable quarter). That tension is working capital. Growing businesses typically need growing working capital, and underestimating that need is one of the most common ways profitable businesses run out of cash.

Three views of working capital

Net Working Capital (NWC)

NWC = Current Assets − Current Liabilities

The standard textbook number. Includes everything on the balance sheet that turns over within 12 months — cash, AR, inventory, prepaids on the asset side; AP, accrued expenses, current portion of debt on the liability side. NWC is what accountants and bankers report.

Operating Working Capital (OWC)

OWC = AR + Inventory − AP

The operational portion that the business directly controls. Excludes cash (which is the result of working capital discipline, not part of it) and short-term debt (which is a financing decision, not an operational one). OWC is the dollar magnitude of what the cash conversion cycle measures in days.

For most owner-operator businesses, OWC is the more useful number to track. It moves directly with operating decisions: tighten AR, OWC drops. Bloat inventory, OWC rises. Negotiate longer supplier terms, OWC drops. NWC moves with these too, but it also moves with cash position and debt structure changes that aren't about the operating cycle.

Days of Working Capital

Days of WC = (OWC / Revenue) × 365

OWC expressed as days of revenue locked up. The cleanest way to compare across businesses of different sizes — a $200,000 OWC means very different things at $1M revenue versus $20M revenue, but a 73-day working capital is comparable.

Days of working capital is also the bridge to the cash conversion cycle. The two numbers are closely related: CCC is computed from DSO + DIO − DPO (days), while days of WC is computed from OWC dollars divided by daily revenue. Both end up in roughly the same place; small differences come from using period-end balances vs. averages, and from CCC using COGS as the denominator for inventory and payables while WC uses revenue throughout.

A worked example

A small manufacturing business with the same numbers as the CCC reference case:

• Revenue: $1,000,000
• Average accounts receivable: $120,000
• Average inventory: $100,000
• Average accounts payable: $50,000

Computing each layer:

OWC = $120,000 + $100,000 − $50,000 = $170,000

Days of WC = ($170,000 / $1,000,000) × 365 = 62 days

For manufacturing, 62 days is well within healthy range (typically 50-115 days). The business is locking up roughly two months of revenue in the operating cycle — typical for manufacturing's inventory-heavy structure.

NWC depends on cash and other balance sheet items. With $80,000 in cash and no other current items, NWC = $170,000 + $80,000 = $250,000. The additional $80,000 is cash buffer; the operational reality is the OWC number.

Working Capital and Cash Conversion Cycle

These two calculators measure the same reality from different angles. Cash Conversion Cycle gives you days; Working Capital gives you dollars. Use both together:

• CCC tells you the efficiency. Are you running 30 days, 60 days, 100 days? Lower is better.
• Working capital tells you the magnitude. How many dollars does that cycle require? This is what sizes your line of credit.
• Together they connect to growth. Adding $1M of revenue at a 60-day CCC requires roughly $164,000 of additional working capital. Knowing that before you grow is the difference between funded growth and a cash crisis.

The calculator above and the Cash Conversion Cycle calculator cross-link automatically — when you have the inputs for one, you can flow into the other with a single click and your numbers carried over.

When working capital matters most

• Sizing a line of credit. The right size of operating LOC is roughly equal to peak seasonal working capital. Owners who don't track WC often end up with LOCs that are too small to bridge seasonal troughs, or too large and expensive in flat periods.
• Modeling growth. Revenue growth almost always requires WC growth at a similar rate. A business growing 30% year-over-year with constant CCC needs 30% more working capital — that money has to come from somewhere (operating cash, line of credit, or owner contribution).
• Acquisition due diligence. Buyers typically require "normalized" working capital at closing — meaning the business has to be handed over with industry-typical WC levels. Below-normal WC reduces the purchase price; above-normal is a working capital adjustment that often surprises sellers.
• Lender covenants. Many commercial loans include a minimum working capital covenant. Falling below it is a technical default. Track quarterly against your covenant level.
• Owner draw planning. The cash that looks available in the bank account often is working capital already committed to the cycle. Drawing down working capital to fund distributions usually surfaces as a problem 60-90 days later.

Common mistakes

1. Confusing NWC with cash. A business can have $300,000 in NWC and almost no cash — most of it is tied up in AR and inventory. NWC is not a measure of available cash; it's a measure of total working capital across all current items.
2. Using period-end balances rather than averages. Year-end balances often look unusually tight or healthy because of seasonal effects or year-end cleanup. Trailing-12-month averages give a more useful number.
3. Ignoring the cash share of NWC. A business with $200,000 of NWC composed of $150,000 cash and $50,000 OWC looks healthy on the surface. But the operational reality is much tighter than NWC suggests. The calculator above flags this when it appears.
4. Treating all current liabilities as the same. Trade AP is operational; current portion of long-term debt is financing; deferred revenue is a customer prepayment. They behave very differently. Component-mode analysis separates these properly.
5. Assuming working capital scales linearly with revenue. It usually does, but inventory-heavy businesses often have step-changes (a new product line or supplier) that move WC disproportionately. Track quarterly during growth periods.
6. Optimizing WC at the expense of operations. Pushing AR collection too hard damages customer relationships; pushing AP terms too far damages supplier relationships; running inventory too thin causes stockouts. The right WC level is industry-typical, not minimum.

FAQ

Is negative working capital bad?

Depends. Negative operating working capital (OWC) is usually exceptional and good — it means suppliers are funding more of the cycle than customers and inventory require. The classic examples are Amazon, well-run quick-service restaurants, and software businesses. Negative net working capital with positive OWC usually signals that current debt or accruals are squeezing the balance sheet — that's a different concern. The calculator above distinguishes these cases.

What's the difference between working capital and cash flow?

Working capital is a balance sheet measure (a stock at a point in time). Cash flow is an income statement measure (a flow over a period). They're related — increases in working capital consume cash, decreases release it — but they answer different questions. WC: how much capital is locked up? Cash flow: how much cash did the business generate this period?

Should I use period-end or average balances?

Averages are more useful for analysis. Period-end (especially year-end) balances are often unusually tight or healthy because of timing effects. Trailing-12-month averages of AR, inventory, and AP give a better operational picture. For lender covenants, use whatever the loan agreement specifies.

How does working capital change as I grow?

Roughly proportionally to revenue, assuming CCC stays constant. A business doubling revenue at constant CCC typically doubles working capital. That's why growth businesses with healthy margins can still run cash-tight — the operating profit gets consumed by working capital requirements faster than it can be banked. Plan for it.

What if I don't hold inventory?

Service businesses with no inventory have OWC = AR − AP. Use 0 for the inventory input. The math works the same way; you just have one fewer component. Service businesses typically have lower working capital requirements than inventory-heavy businesses for the same revenue level.