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Cash runway: calculate months from net burn

Published by Navon Ventures S.A.S · October 27, 2026

Cash runway estimates how long available cash would last at a constant monthly net outflow. The model subtracts monthly cash inflow from monthly cash outflow, then divides available cash by that net burn. It is simpler than a forecast containing individual payment dates and changing balances.

Which inputs to use

Available cash

Use cash available for the modeled purpose. Uncollected invoices are not automatically cash, and restricted funds may require separate treatment.

Monthly cash inflow

Enter cash receipts for a representative month, rather than assuming invoiced revenue is already collected.

Monthly cash outflow

Enter corresponding cash payments in the same currency and scope.

Formula and worked example

Cash ÷ (monthly outflow − monthly inflow)

With $60,000 available, $10,000 monthly inflow and $15,000 monthly outflow, net burn is $5,000. Dividing 60,000 by 5,000 gives 12 months. If outflow becomes $16,000 and other inputs stay unchanged, the estimate falls to 10 months.

Common interpretation mistakes

Dividing cash by total outflow instead of net burn ignores cash coming in and answers a different question. Profit and cash also differ: receivables and payment timing can cause cash strain even in a profitable period. One average month can conceal a large payment due much sooner.

Assumptions and limits

The model excludes seasonality, new financing and one-time changes unless incorporated into another scenario. If inflow meets or exceeds outflow, there is no finite runway under this steady-burn model. That is not a promise of unlimited future cash. Use a dated forecast when individual payment timing matters.

You can also explore Break-even point.