Burn Rate & Runway Calculator
Runway is the startup's most honest clock: cash in the bank divided by what you burn monthly. Compute gross and net burn, months of runway, and roughly when the money runs out.
How to use this calculator
- Enter cash in bank (all accessible accounts).
- Enter total monthly expenses and current monthly revenue.
- Press Calculate — note the fundraise-trigger row: raises take ~6 months.
Formula used
Gross burn is total spending; net burn is what actually leaves after revenue. Runway assumes flat numbers — growing revenue extends it, planned hires shorten it, so treat the figure as a snapshot to re-run monthly.
Example calculation
Cash 2.0 Cr, expenses 25L/month, revenue 9L/month: net burn = 16L → runway = 12.5 months.
With fundraises taking ~6 months, the raise process should start within 6.5 months — runway math is really fundraise-timing math.
Runway as a decision clock
Burn rate turns the bank balance into time, and time is what startups actually spend — every month of runway is a month of experiments, hiring and negotiating leverage. The standard wisdom: start raising with 6+ months left (desperation prices poorly), and hold 18–24 months post-raise so you fund milestones, not survival.
Net burn is the operative number, but gross burn matters in downturns: revenue can vanish faster than costs can, so gross burn is your worst-case clock. The most powerful reframe the math offers: every recurring cost cut is runway purchased at face value.
Why use this calculator?
- Convert the bank balance into months — the unit decisions are made in.
- Get the fundraise-trigger date, not just the cash-out date.
- See the burn target that a desired runway implies.
Frequently asked questions
How much runway should a startup have?
Post-fundraise, 18–24 months is the common target — enough to hit the next milestone set plus a buffer for the raise itself. Below 6 months, extending runway becomes the main job.
Gross burn vs net burn — which do investors ask about?
Both: net burn sets runway, gross burn reveals the cost base's true size and how much revenue is masking it. A company netting 1L burn on 50L gross is far more fragile than one netting 1L on 5L gross.
Does runway math account for growth?
This simple version assumes flat revenue and costs. If revenue grows reliably, actual runway is longer; model it month by month for precision — but for the go/no-go fundraising decision, the conservative flat assumption is the safer planning basis.