Revenue is climbing, headcount is growing, and customers keep signing up. It all sounds great on the surface. But plenty of fast-growing businesses hit a wall, not because demand dries up, but because the money behind the growth was never properly tracked. The difference between founders who scale smoothly and those who stall usually comes down to a handful of numbers.
1. Gross Margin
Gross margin tells you what’s left from revenue once you’ve paid for the direct costs of delivering your product or service. The formula is simple: (revenue minus cost of goods sold) divided by revenue, shown as a percentage.
Where founders get caught out is assuming that more sales automatically means more profit. If your margins are thinning as you grow, whether through supplier price hikes, rising fulfilment costs or aggressive discounting, you could be scaling into a loss without realising it. Track this monthly and flag any downward trend early. A business turning over £2m at 25% gross margin has far less breathing room than one doing £1m at 55%.
2. Current Ratio
Your current ratio measures whether you can cover short-term debts with short-term assets. It’s current assets divided by current liabilities. A ratio above 1 means you can, in theory, pay what you owe over the next 12 months.
But the headline number can be misleading. A current ratio of 2.5 might look comfortable on paper, yet if most of those assets are tied up in slow-moving stock, the picture changes fast. Strip out inventory and recalculate. That gives you the quick ratio (sometimes called the acid-test ratio). If it drops sharply below the current ratio, your actual liquidity isn’t as strong as the spreadsheet suggests. For scaling businesses carrying a lot of stock, this distinction really matters.
3. Debt Service Coverage Ratio
The debt service coverage ratio (DSCR) shows whether your business earns enough to meet its debt repayments. You calculate it by dividing net operating income by total debt service (that’s principal plus interest). Most lenders want to see a DSCR of at least 1.25 before they’ll lend.
This ratio matters most when you’re planning to borrow. Any lender assessing an application for a large business loan in the UK will look at DSCR closely, so track it well before you actually need the funds. If your DSCR is sitting below 1, you’re earning less than your current repayments require. That will make any new borrowing very difficult to secure, regardless of how strong your revenue growth looks.
4. Debtor Days
Debtor days tells you how long, on average, your customers take to pay you. The formula is (trade receivables divided by annual revenue) multiplied by 365.
A rising debtor days figure is one of the most common cash flow traps in growing businesses. You’ve done the work, sent the invoice, and booked the revenue on paper, but the money hasn’t landed. Meanwhile, your suppliers and staff still need paying on time.
If debtor days are creeping up past 45 or 60 (and your sector doesn’t routinely operate on longer payment cycles), tighten your payment terms, chase invoices harder, or consider invoice finance to bridge the gap.
5. Operating Cash Flow
Operating cash flow (OCF) strips out financing and investment activity to show how much cash your business generates from its day-to-day operations. You’ll find it on the cash flow statement, or you can work it out from net income adjusted for non-cash charges and working capital changes.
This is the number that keeps founders honest. A business can report a healthy profit and still run out of cash, especially when it’s growing fast and tying up money in stock, hiring or new equipment. If OCF has been negative for several months while profits look fine, something is off. That disconnect between reported profit and actual cash in the bank is usually where serious problems begin.
Five Numbers, One Clearer Picture
No single ratio will give you the full story. But together, these five cover the ground that matters: profitability, liquidity, borrowing capacity, payment cycles and real cash generation.
The biggest mistake scaling founders make is treating these numbers as something for year-end accounts or board packs. By then, it’s often too late to course-correct. Check them monthly, question what’s behind them, and use them to decide when to push forward and when to pull back.
