Most UK SME owners track too many metrics or the wrong ones. This guide covers the 10 commercial KPIs that actually predict whether a business is healthy, growing, and resilient — and what to do when any of them moves in the wrong direction.
Revenue minus direct costs, expressed as a percentage of revenue. The foundation of everything. If gross margin is too low, every other metric is harder — there is not enough surplus to cover overheads, fund growth, or absorb shocks. Check monthly. Act if it moves more than 2 percentage points in either direction.
What remains after all costs. The minimum viable threshold for most UK SMEs is 5-8%. Below this, the business has no buffer. Above 15%, the business is generating genuine surplus. The gap between gross and net margin reveals the overhead burden — the most controllable variable in the P&L.
Current cash balance divided by monthly fixed costs. How long the business could survive if revenue stopped tomorrow. Minimum recommended: 2 months. Target: 3 months. Below 1 month: immediate risk management required.
How long customers take to pay. Calculated as: (debtors ÷ annual revenue) × 365. UK SME benchmark: 30-45 days. Above 60 days signals a collection problem. Every extra 15 days adds approximately 4% of annual revenue to the cash tied up in debtors.
The minimum monthly revenue to cover all costs. Calculated as: fixed costs ÷ gross margin %. Essential for understanding how much buffer the business has above the floor. A business trading at 110% of break-even has almost no resilience. At 150% of break-even, it has meaningful protection.
Total revenue divided by headcount. A measure of operational efficiency. UK SME benchmark varies widely by sector: professional services £100-200k, distribution £200-400k, retail £150-250k. Falling revenue per employee signals either revenue decline or overstaffing.
Gross profit generated per £1 of marketing spend. Must be calculated on gross profit, not revenue. Break-even profit ROAS = 1.0x. Strong performance = above 1.5x. Below 1.0x means marketing is consuming more gross profit than it generates.
How many times inventory is sold and replaced per year. Calculated as: cost of goods sold ÷ average inventory value. Low turnover means cash is locked in slow-moving stock. High turnover with frequent stockouts means the business is leaving revenue on the table.
Customer Lifetime Value divided by Customer Acquisition Cost. Minimum viable: 3:1. Strong: 5:1. Above 10:1 typically means under-investment in growth. Below 1:1 means the business loses money on every customer acquired — a structural problem that gets worse with scale.
The ratio of fixed to variable costs. High fixed costs mean revenue growth delivers disproportionate profit growth — but revenue declines are equally painful. Understanding your operating leverage determines how aggressively you can grow and how much buffer you need against downside.
Every KPI on this page is calculated automatically by the LumixAI tool suite. See your numbers clearly in one place.
Start your free trial →Gross margin, cash balance, and debtor days: monthly minimum. Break-even, net margin, and revenue per employee: quarterly. LTV:CAC and stock turnover: quarterly or when making acquisition or purchasing decisions. Operating leverage: when considering significant fixed cost commitments (hires, premises, equipment).
The LumixAI Free AI Business Review calculates your gross margin, net margin, cash runway, and break-even from five inputs in under 60 seconds — a useful starting point for any business that wants a quick read on where the numbers stand.