Cash Burn Runway Calculator

Runway is how long a business can operate at its current burn rate before running out of cash. For startups and early-stage companies, runway is the most important single metric because it sets the urgency of every other decision: fundraising timing, hiring cadence, marketing spend, product bets. A company with 24 months of runway runs the business differently than a company with 6. This calculator does the straightforward division and adds a revenue-growth projection that shows how runway extends as revenue catches up to expenses.

Enter current cash balance, monthly operating expenses, current monthly revenue, and an optional monthly revenue growth percentage. The output shows monthly net burn (expenses minus revenue), flat-revenue runway in months, growth-adjusted runway that simulates revenue growing at your input rate while expenses stay flat, and a projected cash-out date. A runway capped at 120 months is shown as infinite; the cap exists because the simulation is not informative beyond that point.

Common runway targets at different stages vary, but the general rule is that fundraising typically takes 3-6 months and should begin with a reasonable runway buffer remaining so the company is not negotiating from a position of weakness. Pair with the break-even analysis calculator for the path to eliminating burn entirely.

Monthly net burn = max(monthly_expenses - monthly_revenue, 0). A company whose revenue exceeds expenses has no net burn and is not consuming cash, so flat-revenue runway is effectively infinite.

Flat-revenue runway = cash_balance / monthly_net_burn. Simple division. Assumes both expenses and revenue stay constant, which is almost never true but gives the worst-case number to plan against.

Growth-adjusted runway is a month-by-month simulation. Each month: subtract (expenses - current_revenue) from cash, then multiply current revenue by (1 + growth_pct). Continue until cash hits zero or 120 months elapsed. This gives a more realistic runway when the business is genuinely growing. If monthly revenue growth exceeds the ratio of expenses to revenue, revenue eventually overtakes expenses and runway becomes effectively infinite (capped at 120 months in the display).

Projected cash-out date = today + floor(flat_runway) months, formatted as month and year. Useful for setting fundraise targets and board-meeting agendas. Growth-adjusted cash-out is not shown as a date because the date depends nonlinearly on the growth assumption.

Use this monthly or at least quarterly to track runway trend, before making a major hire or signing a new lease to see the runway impact, and at the start of every fundraise cycle to set the timeline. Fundraising convention is that you should begin the raise with at least 6 months of runway remaining so you have time to close without signing a desperation term sheet. For the unit-economics side of the same business, pair with the profit margin calculator and break-even analysis.