Cash flow runway calculator.

How this calculator works (same formula nouz uses).

Runway is the number of months your cash lasts before you can't pay rent. It is the most important figure to know when business is shaky — and the easiest to ignore when business feels fine, which is precisely when you should be checking it, because that is when you still have room to act.

The math is deliberately blunt: Net burn = monthly costs − monthly revenue, then Runway months = cash on hand ÷ net burn. If revenue covers costs, burn is zero or negative and runway is effectively infinite at the current rate. If costs outrun revenue, the calculator tells you how many months the bank balance buys you before it hits zero — and roughly what date that is if nothing changes.

A worked example

Using the defaults: €24,000 cash on hand, average monthly revenue of €38,000, monthly fixed costs of €14,000, and monthly variable costs of €27,000. Total monthly costs are 14,000 + 27,000 = €41,000. Net burn is 41,000 − 38,000 = €3,000 a month — the shop is spending €3,000 more than it brings in. Runway is 24,000 ÷ 3,000 = 8.0 months. In plain terms: at this rate the account empties in about eight months, so a fix has to be in motion long before then, not on the last day.

What a healthy number looks like

Read the number against these bands. Under 3 months is an emergency — cut costs hard, raise prices, or arrange a credit line this week. 3 to 6 months is caution — build a concrete plan to grow revenue or cut costs by month-end. 6 to 12 months is healthy — you have time to make thoughtful decisions rather than panicked ones. 12+ months means you can invest in growth without sweating. As a rough rule of thumb, most small shops sleep better keeping at least three to six months of runway in reserve. The eight months in the example above sits in the healthy band, but note how fragile it is: because burn is only €3,000 against €41,000 of costs, a 10% dip in revenue roughly doubles the burn and halves the runway, so small swings in sales move this number a lot.

Common mistakes

• Confusing "profitable" with "safe." A profitable P&L can still run out of cash through a tax bill, slow receivables, or a loan repayment.
• Using an optimistic revenue figure. Runway is a floor — base it on a normal or slow month, not your best one.
• Forgetting lumpy costs. Quarterly VAT, annual insurance and stock-up orders all raise the true burn above a smooth monthly average.
• Checking only in a crisis. Runway is cheapest to extend when it is still long, not when it is nearly gone.

When to use it — and what's next

Check runway monthly against your actual bank balance, not what the P&L says you "should" have — the whole point is spotting trouble while you still have months to steer. To keep the revenue and cost figures it needs current and honest, log your days in the daily profit and loss template, and drill into the profit side with the daily profit calculator and the break-even calculator.