How many months you can keep the lights on without any new sales.
Cash runway is the single most important survival number for a small business. It answers: 'if no money comes in tomorrow, how long can I pay everyone?' Knowing it changes the conversations you have about hiring, leasing, marketing spend, and whether you actually need that contract you've been chasing.
Operator Tools' Cash Runway Calculator works it out from your current cash balance, your monthly burn rate (the gap between fixed costs and gross profit on existing sales), and your safety threshold — the cash you want to keep on hand even at the bottom.
Runway = (current cash − safety threshold) ÷ monthly burn. Burn is the net monthly outflow: total fixed costs minus the gross profit your existing sales reliably generate. Once burn is positive (you're losing money each month), runway is finite; if burn is zero or negative (you're profitable), runway is effectively unlimited.
Enter your current cash balance (cash in the bank, today)
Enter your safety threshold
The minimum cash you want to keep on hand even at the bottom — for an emergency, a tax bill, payroll for one cycle.
Enter your monthly fixed costs
Enter the gross profit your existing sales reliably bring in
Be honest — the number you can count on, not the optimistic forecast.
Read your runway in months, plus the risk colour code and recommendation
Most advisors say 3 months is the absolute minimum, 6 months is comfortable, and 12+ months is the level at which you can make calm strategic decisions. Below 3 months, every operational decision becomes about staying alive.
No — only count cash actually in the bank. Invoices outstanding aren't cash until they're paid, and overdue invoices in particular are a leading indicator of cash trouble, not a source of cash.
A cash flow forecast projects exact ins and outs over time, week by week. Cash runway is a single number that summarises 'how long do I have at my current rate'. Use runway monthly for a fast pulse check; use a forecast when you need to plan around specific upcoming bills.
It's a paid tool, included in Founding Lifetime Access (€99 one time, no subscription). The free tier covers the Business Health Score, Profit Margin Calculator, and Break-Even Calculator.
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