Startup runway estimates how long available cash can support a company at its current net cash burn. Divide usable cash by monthly net burn for a basic estimate. Then test planned spending, collection delays and financing assumptions, because a historical average can hide a cash shortage before the next milestone.
When reviewing companies through startup investment platforms, use runway as one part of diligence. A platform's access rules and a startup's funding needs answer different questions. Neither a long runway nor a recently completed round proves that the investment will succeed.
Define gross burn and net burn consistently
Gross burn measures the cash a business spends over a period. Net burn deducts operating cash receipts from the relevant cash outflows. For a cash-runway model, use actual cash movement rather than treating booked revenue as money already received.
Stripe explains gross and net burn and their role in funding analysis. Financial presentations use different definitions, so ask which expenses, receipts and financing movements the company includes.
Revenue recognised on an unpaid invoice does not fund this month's payroll. Equally, a loan or equity raise increases cash without demonstrating stronger customer collections. Keep financing inflows separate from the operating burn measure.
Use the same currency and period throughout the calculation. A weekly cost report and monthly revenue figure need alignment before subtraction.
Build a basic runway calculation
The simple formula is available cash divided by monthly net burn. It is useful when cash use is reasonably stable. Pilot's runway calculator illustrates the formula and explains why runway needs recalculation after financing or spending changes.
Consider an illustrative startup with $900,000 of usable cash. Its monthly operating cash outflows are $150,000, while cash collected from customers is $60,000. Net burn is $90,000 per month, giving a simple runway estimate of ten months.
Input or measure | Illustrative amount |
|---|---|
Usable cash at the measurement date | $900,000 |
Monthly operating cash outflows | $150,000 |
Monthly customer cash receipts | $60,000 |
Monthly net cash burn | $90,000 |
Estimated runway at unchanged burn | 10 months |
This calculation excludes new financing and assumes unchanged monthly receipts and spending. It does not predict an exact date of insolvency. A large payment can create a problem inside the estimated period even when the monthly average appears manageable.
Check which cash is actually available
The starting cash figure should represent money the company can use for the costs in the model. Reconcile the figure to dated account records and identify restricted or unavailable amounts.
Suppose the startup reports $1.1 million across its accounts, but $200,000 is unavailable for ordinary operating payments. Using the full balance would suggest about 12.2 months at $90,000 burn. Using the $900,000 available amount gives ten months.
This difference is an arithmetic consequence of the assumption, not a claim about a particular company's restrictions. Ask management to explain the status of each excluded amount.
Also establish whether figures are consolidated across legal entities. Money in one subsidiary may not be immediately usable by another. An undrawn credit facility and an unsigned investment proposal should not be silently treated as cash in the bank.
Replace the average with a monthly forecast
A monthly cash forecast shows when money moves. Build it from opening cash, expected receipts, operating payments and separately identified exceptional or financing items.
Here is a continuation of the illustrative example. The startup plans a product launch that raises its near-term spending. All amounts are in US dollars; no new financing is assumed.
Month | Opening cash | Net cash use | Closing cash |
|---|---|---|---|
Month 1 | $900,000 | $90,000 | $810,000 |
Month 2 | $810,000 | $120,000 | $690,000 |
Month 3 | $690,000 | $180,000 | $510,000 |
Month 4 | $510,000 | $120,000 | $390,000 |
The company uses $510,000 in four months. A flat historical model would have projected $540,000 remaining; the monthly plan shows $390,000. Repeating the old ten-month runway without discussing the launch would hide this change.
Retain one-off costs as visible cash items. Excluding them from a normalised burn metric does not remove the need to pay them.
Test a downside without inventing a forecast
A downside test changes explicit assumptions and measures the cash effect. It is a scenario, not a prediction or a probability estimate.
For the original $900,000 example, assume customer receipts fall from $60,000 to $40,000 while monthly outflows stay at $150,000. Net burn becomes $110,000, reducing the simple runway to approximately 8.2 months.
If management instead plans to cut spending, ask when the reduction affects cash. A decision to reduce a contract does not necessarily stop next month's payment. Hiring commitments, notice periods and supplier terms can delay the benefit.
First Citizens' discussion of startup burn treats cash use in the context of growth and operating decisions. A low burn figure is not inherently good if the company cannot reach a useful milestone. A high burn figure needs an explanation tied to results and financing capacity.
Connect runway to the next evidence producing milestone
The investor's question is whether the funded plan can reach a meaningful milestone before cash becomes constrained. Identify the milestone, its required spending and the evidence that will demonstrate completion.
For example, a launch may require development, approvals and initial customer support before collections increase. Ask whether the forecast includes all three. A model that funds development but omits the next operating stage can overstate what the current cash achieves.
First Citizens' financial management guidance emphasises cash visibility, spending controls and reporting discipline. Those controls help assess whether management can update its plan when assumptions change.
What to request when the numbers do not reconcile
Request dated cash balances, recent monthly cash movements, the forward cash forecast and the definition of burn used in the investor materials. Ask management to bridge differences between the reported runway and your calculation.
Document which answer depends on signed contracts, collection estimates or future fundraising. A forecast should show the effect of financing arriving later than planned. Until funding is completed and usable, the company still needs a plan for the cash it actually controls.