Runway Calculator

The most important number a founder tracks

Ask any experienced founder what keeps them awake at night, and the answer is rarely the product — it is the runway. Runway is the number of months a startup can keep operating before its cash runs out, and it sits at the centre of nearly every strategic call: when to hire, when to raise, how aggressively to grow. The calculation is disarmingly simple. Take your current cash, subtract revenue from burn to find your net monthly burn, and divide. The result is your countdown.

Net burn is what matters

Early on, a startup often has no revenue, so its net burn equals its gross spending and the runway calculation is stark. But as revenue arrives, it offsets the burn, and net burn — not gross burn — becomes the true driver of survival. A company spending ₹12 lakh a month but earning ₹8 lakh has a net burn of only ₹4 lakh, and its cash lasts three times longer than the gross figure suggests. This is why growing revenue is every bit as powerful as cutting costs: both shrink net burn and stretch the runway.

The ultimate milestone is when revenue matches or beats burn. At that point net burn falls to zero, the cash stops depleting, and runway becomes open-ended — the business has reached cash-flow positivity and is no longer racing a clock.

Reading the countdown

A startup with ₹50 lakh in the bank and a ₹12 lakh net burn has roughly 4.2 months of runway. That is a warning light, not a comfort — well short of the 12 to 18 months most investors like to see after a round. The Indian fundraising cycle typically takes three to six months to close, so the widely followed discipline is to begin the next raise with at least six months of runway remaining. Starting early means negotiating from strength; waiting until the cash is nearly gone means negotiating from desperation, usually on far worse terms.

Keeping runway honest

Runway is only as reliable as the assumptions behind it. This calculation freezes today's burn and revenue in place, but in a scaling business both move constantly — new hires lift burn, a strong quarter lifts revenue. Treat the figure as a live gauge, not a one-time reading: recompute it every month, strip out unusual one-off cash movements, and model optimistic and pessimistic revenue paths so you understand how your runway stretches in a good scenario and collapses in a bad one. Managed with that discipline, runway becomes the compass that tells an Indian startup exactly how much time it has to prove itself — and precisely when to act.