Direct answer
Cash runway estimates how many periods an available cash balance can fund a stated net cash burn; it is a scenario horizon that changes whenever cash receipts, spending or minimum reserves change.
What this calculation tells you
Burn rate describes cash consumption over a defined period, especially when operating outflows exceed inflows. Runway translates that pace into time before an entered reserve is reached.
A historical average can smooth noise but may miss a recent hiring plan, annual bill or falling revenue. A forward monthly schedule is stronger than blindly extending the last number.
Where it is used
Startups
Connect hiring, product development and fundraising timing with available unrestricted cash.
Turnarounds
Measure the time available for cost, pricing or collection actions to change the trajectory.
Seasonal businesses
Plan through low-revenue months while distinguishing recurring burn from seasonal working capital.
Project-based firms
Test the effect of delayed milestones, deposits and uneven payroll commitments.
When this guide helps
- A funding round closes later than planned.
- Management considers adding fixed payroll.
- Revenue is growing but cash burn also rises.
- A minimum operating reserve must remain untouched.
Choose the cash balance that is truly available
Remove restricted balances and any minimum reserve the business is unwilling to spend. Add only committed financing when its conditions and timing are sufficiently certain for the scenario.
Distinguish gross and net burn
Gross burn highlights total cash operating outflow; net burn reflects the excess of outflows over inflows. Two businesses with the same net burn can have very different scale and risk.
Model a changing burn profile
Use month-by-month amounts when contracts, hires, annual renewals, tax payments or seasonality matter. A constant-rate runway is a quick sensitivity, not a complete forecast.
Plan trigger points before zero
Funding and cost actions take time. Set decision thresholds for cash, collections, revenue and milestones well before the modeled depletion date.
- Keep a base, downside and severe case.
- Update actuals monthly.
- Do not count unsigned funding.
Worked case: current burn
Available cash is 240,000 and monthly net burn is 40,000.
Runway=240,000/40,000=6 months.
The entered constant-burn runway is six months.
It is not a promise that every bill can be paid through the exact month-end date.
Reproduce this worked caseOpen Burn Rate Calculator
Worked case: reduce burn
Net burn falls to 30,000 with cash unchanged.
Runway=240,000/30,000=8 months.
The scenario extends arithmetic runway by two months.
One-time restructuring cost and delayed savings must be dated separately.
Reproduce this worked caseOpen Burn Rate Calculator
burn rate and runway: compare assumptions, not just answers
Use a dated cash forecast when payroll, taxes, financing or collections are lumpy. Gross spend and net burn should not be confused.
| Scenario | Key input | Decision output |
|---|---|---|
| Current | 40 thousand/month | 6 months |
| Reduced | 30 thousand/month | 8 months |
burn rate and runway: calculation checklist
- Cash truly available
- Gross and net burn labelled
- One-time costs dated
- Expected funding not assumed
- Zero/negative burn handled
Practical questions
Frequently asked questions
Should runway use gross or net burn?
Runway usually uses net cash burn, while gross burn remains useful for understanding the spending base and operational scale.
What if net burn is zero or negative?
A constant-burn runway is not finite when inflows meet or exceed outflows, but future changes and one-off obligations still need forecasting.
Does twelve months of runway mean the business is safe for twelve months?
No. Collections, costs, financing availability and strategic needs can change before the arithmetic horizon.
Further reading
Authoritative sources
Use these primary and professional resources to check definitions, conventions, or requirements that may extend beyond this guide.