Runway & Burn Rate Calculator

Inputs

Month-by-month projection

Assumes revenue grows at the rate above each month and expenses stay flat.

Month	Revenue	Expenses	Cash left

Runway is a snapshot, not a guarantee

Net burn is what's actually left over each month after revenue — expenses minus revenue. Runway (cash ÷ net burn) tells you how many months you have left if nothing changes. The moment revenue, expenses, or growth rate shifts, the real number shifts too — this calculator's month-by-month table exists specifically to make that growth assumption visible, since a single "months of runway" figure hides whether it's flat, improving, or worsening.

How to use it

• Under 6 months of runway is generally considered critical — most founders start cutting costs or raising well before hitting this point, since fundraising itself takes months.
• 12-18 months is a common comfort zone that gives room to adjust course without an immediate cash crisis.
• Model a conservative growth assumption, not an optimistic one — runway calculators are most useful as a downside check, not a best-case projection.

Common mistakes

• Assuming a flat growth rate holds for the full projection window — growth (and burn) rarely stay linear for 12-24 months in either direction.
• Excluding one-time or lumpy expenses (annual software renewals, contractor payouts, taxes) from the monthly expense figure, which makes runway look longer than it actually is.
• Confusing net burn with gross burn (total expenses, ignoring revenue) — gross burn matters for understanding cost structure, but net burn is what determines how long the cash actually lasts.