Cash crunch warning signs: the ratios that catch trouble early

Cash crunches don't appear out of nowhere

Talk to enough small business owners who've survived a cash crisis, and a pattern emerges. The crisis itself feels like it came out of nowhere — one Tuesday morning, payroll is in 48 hours, and the bank account isn't going to cover it. But when you walk back through the previous six months with them, the warning signs were there. Receivables had been creeping up. The current ratio had drifted from 1.8 down to 1.1. Cash was tighter every month even though the P&L looked fine.

The owners who survive cash crunches are not the ones who react fastest in the crisis. They're the ones who caught the warning signs at month two or three, when the fix was cheap, instead of month six when the only options left were expensive ones.

This guide walks through the four ratios that, watched monthly, will catch a cash crunch before it's a crisis. A five-minute review per month is enough. The hardest part isn't the math; it's the discipline to actually look.

Why “profitable” businesses run out of cash

Cash crunches in profitable businesses almost always come from one root cause: working capital is silently absorbing cash. Your customers owe you more than they used to. Inventory has crept up. You're paying suppliers slightly faster than you used to. Each of these consumes cash without showing up on the income statement.

The income statement says you made $200K of profit last year. The bank account says cash dropped by $50K. The difference is $250K of working capital growth — cash that's real but trapped in receivables, inventory, and earlier-paid bills. The income statement is right; the bank account is right; they're measuring different things.

More on the underlying mechanics in the profit-vs-cash guide. The point for this guide: working capital ratios are the early-warning system for the cash gap that profit alone can't see.

Warning sign 1: DSO creeping up

Days Sales Outstanding measures how long, on average, your customers take to pay you after you've invoiced them. The formula:

DSO = (Accounts Receivable / Annual Revenue) × 365

Track DSO every month. The absolute number depends on your industry and terms — a manufacturer on net-60 might run 65–75 days; an ecommerce business on credit cards might run under 5 days. The number itself matters less than the trend.

The warning levels:

Yellow: DSO is 5 days higher than your industry typical, or 5 days higher than your own 12-month rolling average. One or two big customers stretching their terms can move the number this far. Investigate.
Red: DSO is 10+ days higher than baseline and trending up for two or more consecutive months. This isn't one slow-paying customer; it's a pattern. Your collection process or your customer mix is shifting, and your cash position is being absorbed by it.
Fire alarm: DSO is 20+ days higher than baseline. At this level, the AR balance has likely doubled or more from where it was, and the cash impact is significant.

What to do at each level: at yellow, pull an AR aging report and call the top three slow-payers. At red, audit your invoicing process — are invoices going out within 24 hours of work being completed? Are payment terms being enforced? At fire alarm, this is the priority that comes before everything else this week.

Warning sign 2: Current ratio drifting toward 1.0

The current ratio is the most direct test of short-term solvency: do your current assets (cash, AR, inventory) cover your current liabilities (bills due in the next 12 months)? A ratio of 1.0 means “just barely.” Below 1.0 means “not really.”

The ratio drifting downward is one of the most reliable predictors of a future cash crunch, because the underlying mechanism is exactly what causes crunches: liabilities growing faster than assets, slowly, month after month.

The warning levels:

Yellow: Current ratio dropped 0.3 or more in the last six months, even if the absolute number is still healthy. A move from 2.5 to 2.1 is a yellow flag — not because 2.1 is bad, but because thedirection is the same direction that ends in trouble.
Red: Current ratio is between 1.0 and 1.3. The business is solvent but has very little buffer. Any negative surprise — a customer paying late, an equipment failure, a slow month — pushes you below 1.0.
Fire alarm: Current ratio is below 1.0. The business owes more in the next 12 months than it has resources to pay from current assets alone. Action is required this month, not this quarter.

The trick with current ratio is that it can drift slowly and look fine at any single snapshot. A business that drifts from 1.8 to 1.6 to 1.4 to 1.2 over four quarters looks “okay” at every single quarter-end — but the trajectory is the cash crunch. Watch the trend, not just the level.

Warning sign 3: Cash conversion cycle increasing

The cash conversion cycle (CCC) measures how long, in days, cash is tied up between when you spend it (paying suppliers, building inventory) and when it comes back (customers paying their invoices). The formula:

CCC = DSO + DIO − DPO

(Days Sales Outstanding + Days Inventory Outstanding minus Days Payable Outstanding.) A CCC of 60 means cash is, on average, gone for 60 days before it comes back. A CCC of 0 means receivables and inventory are funded entirely by payables. A negative CCC — common in retail and ecommerce — means your customers pay before you have to pay your suppliers, which is essentially free working capital.

The CCC increasing is a clearer signal than any single component, because it accounts for all three working capital levers at once. DSO might creep up (bad), but DPO might also extend (good), and the net effect on cash might be neutral. CCC tells you the net.

The warning levels:

Yellow: CCC is 5–10 days higher than your 12-month rolling average. Working capital is absorbing cash, but the rate is manageable.
Red: CCC is 10+ days higher and trending up for three or more consecutive months. The business is structurally needing more cash to operate, even at the same revenue level.
Fire alarm: CCC has risen 20+ days from baseline. At typical revenue scales, that translates into a working capital need that's 50–100% higher than it was. Without a corresponding cash buffer or credit line, the math gets ugly fast.

The diagnostic question for a rising CCC: which of the three components is moving? If DSO is rising and DPO is flat, your customers are paying you slower without you stretching suppliers to match — that's the customer-financing trap. If DIO is rising, inventory is accumulating — either you're building safety stock you don't need or sales are slowing while purchasing keeps the same pace. If DPO is dropping, you're paying suppliers faster than before, which is sometimes intentional and sometimes a sign of vendor leverage shifting.

Warning sign 4: The cash flow / net income gap

The fourth warning sign isn't a single ratio — it's the gap between the income statement and the cash flow statement. Specifically: net income versus operating cash flow.

In a healthy, stable business, operating cash flow should track reasonably close to net income over a 12-month period. They won't be identical because of timing, but they should be in the same ballpark. When operating cash flow is materially below net income, working capital is silently absorbing the difference.

Pull this from your cash flow statement (most accounting software produces it; few owners look at it). Look at the 12-month trailing operating cash flow versus the 12-month trailing net income. The ratio is what matters:

Operating cash flow / Net income above 0.85: healthy. Most reported profits are converting to actual cash within a reasonable window.
Between 0.6 and 0.85: yellow. A meaningful chunk of profit is sitting in working capital. Investigate which line.
Below 0.6: red. The cash gap is large enough that the business is functionally less profitable than it appears. Sustainable only if the working capital growth is intentional (e.g., you're scaling fast and building inventory deliberately) and there's a corresponding cash buffer or credit facility.
Operating cash flow consistently negative while net income is positive: fire alarm. The business is profitable on paper but consuming cash from operations every month. Something is structurally broken.

The five-minute monthly review

Once a month, around the same time you reconcile your bank account, spend five minutes on this. The discipline alone is worth more than the math.

Pull the four numbers from your accounting software: AR balance, current asset / current liability balances, the three CCC components (AR, AP, inventory) at current values, and 12-month trailing operating cash flow vs. net income.
Compute the four ratios: DSO, current ratio, CCC, OCF/NI ratio. (The calculators on this site do this in under a minute each.) Or compute the change from last month and last quarter.
Compare to your 12-month rolling average for each. The level matters less than the direction.
Note any yellow or red flags in a running document — a notes file, a spreadsheet, anything. The point isn't to be exhaustive; it's to surface the trend month over month.
If two or more ratios are flagging, set aside an hour this week to investigate. If one is flagging in red or fire alarm, address it before doing anything else this week.

That's it. Five minutes a month. Most owners won't do it because it sounds boring; the ones who do it almost never get caught by surprise cash crunches.

A worked example: catching it in time

A small manufacturing business, $3.2M in revenue, makes a specialty industrial component. Owner does the books once a quarter with the help of a part-time bookkeeper. P&L shows steady profit; bank account shows steadily declining cash. Owner hasn't connected the two.

Six months of monthly data:

Month 1: DSO 45 days, current ratio 1.8, CCC 62 days. All within normal range.
Month 2: DSO 48, current ratio 1.7, CCC 65. Subtle drift but nothing alarming.
Month 3: DSO 52, current ratio 1.6, CCC 70. Yellow flag on DSO (drift of 7 days from month 1). This is where a monthly review catches it.
Month 4: DSO 56, current ratio 1.5, CCC 74. Red on DSO. Yellow on CCC. Investigation reveals two new large customers paying on net-60 instead of net-30, plus inventory buildup from a misread sales forecast.
Month 5: Owner has acted — tightened terms with one customer, reduced inventory orders, started calling AR aging weekly. DSO 53, current ratio 1.55, CCC 70. Trend reversing.
Month 6: DSO 49, current ratio 1.7, CCC 64. Back to baseline. Cash crisis averted.

Without the monthly review, this business would have spent another 3–4 months drifting in the wrong direction before the bank account screamed loud enough to force attention. By that point, the AR balance would have ballooned, inventory would have peaked, and the credit line would have been getting close to maxed. Solving the same problem from that position is much harder.

The single best preventive habit

The four ratios are the early warning system. The single best preventive habit is a layer above that: a 13-week rolling cash flow forecast, updated weekly.

A 13-week forecast lists every expected cash inflow and outflow for the next quarter, by week. Customer payments (with realistic timing based on actual DSO, not your invoice terms). Vendor payments. Payroll. Tax payments. Loan payments. Anything else. Updated weekly so the forecast stays current.

What it gives you that the four ratios don't: a bottom-line cash position projection, week by week, that shows you when you'll be tight before you're tight. The discipline of building it forces you to look at your AR aging, your AP aging, and your near-term obligations all in one place. The first time you build one is painful; the tenth time it takes 20 minutes.

A 13-week cash flow template is part of the OwnerNumbers Toolkit, along with a guided wizard to fill it in from your accounting software.

The bigger point

Most cash crises in profitable businesses are not bolts from the blue. They are slow, predictable drifts that the ratios pick up months in advance. The owners who get caught are not unlucky — they're the owners who didn't look at the ratios until the bank account forced them to.

Five minutes a month, four ratios, a running notes file. That's the entire preventive system. No software required, no advanced finance training, no expensive consultant. The discipline is what costs — and the alternative cost (a real cash crunch) is much higher.

For a structured run through these four ratios plus everything else that affects cash position, see the Financial Health Check — it computes them all, flags anything outside healthy range, and produces a printable report you can review with your bookkeeper or accountant.