Cash Runway Tracking When Your Burn Rate Won't Sit Still

Cash runway is the number of months a company can keep operating before its cash runs out, assuming current spending and collections continue. It is calculated by dividing the cash balance by average monthly net burn. Runway tracking means recalculating that figure on a regular cadence as actual cash flows change.

The formula is simple. The hard part is that the inputs move. Burn rises when you hire, falls when a large customer pays early, and jumps when an annual software contract renews. A runway number calculated once a quarter can be off by months by the time anyone acts on it.

This guide covers how to calculate runway, the difference between gross and net burn, a worked example, and a tracking cadence that keeps the number honest.

How to calculate cash runway

Cash runway (months) = cash balance ÷ average monthly net burn

Three definitions matter:

• Cash balance is unrestricted cash and cash equivalents you can spend. Exclude cash pledged as collateral, held in escrow, or trapped in an entity you cannot easily move it out of.
• Gross burn is total cash going out in a month: payroll, rent, vendors, software, debt service, taxes.
• Net burn is gross burn minus cash coming in from customers and other operating sources. A company that spends $500,000 and collects $300,000 has a net burn of $200,000.

Use net burn for the headline runway figure. Use gross burn as a stress test: it tells you how long you would last if collections stopped, which is the scenario a lender or board will ask about when a large customer is late.

Use a trailing average (usually three months) rather than a single month. One month can be distorted by a quarterly tax payment, an annual prepayment, or a payroll month with three pay dates. A three-month average smooths those without hiding a real trend.

Example: runway for a hypothetical 40-person SaaS company

Example: a hypothetical 40-person SaaS company ends June with $3,600,000 in the bank. Its last three months of cash activity:

The arithmetic:

• Net-burn runway (trailing average): $3,600,000 ÷ $230,000 = 15.7 months.
• Net-burn runway (June only): $3,600,000 ÷ $240,000 = 15.0 months.
• Gross-burn runway (no collections): $3,600,000 ÷ $540,000 = 6.7 months.

Two things stand out. First, net burn is rising by $10,000 a month, so the trailing average already overstates runway compared with the latest month. If the trend continues, the real figure is lower than 15 months. Second, the gap between 15.7 months and 6.7 months is the company's dependence on collections. About nine months of runway (15.7 minus 6.7) rests on customers paying on time.

That is why a single runway number is not enough. Report the trailing figure, the latest-month figure, and the gross-burn floor together, and note the direction of travel. You can run the same calculation with your own numbers in our free cash runway calculator.

Why runway numbers go stale

Runway rarely goes wrong because of a bad formula. It goes wrong because the inputs drift between updates.

Burn changes faster than the update cycle. A quarterly runway review misses a hire made in week two, a price increase from a key vendor, or a customer that moved from monthly to annual billing. Each changes net burn the month it happens.

Collections are uneven. The Federal Reserve's 2025 Report on Employer Firms, based on the 2024 Small Business Credit Survey, found that 51% of employer firms cited uneven cash flows as a financial challenge, and 56% cited paying operating expenses. The survey's definition of uneven cash flow explicitly includes collecting on receivables. When cash in is lumpy, a runway figure built on one good month is fragile.

Forecasting itself is hard, even for specialists. In the 2026 AFP Treasury Benchmarking Survey, cash and liquidity forecasting was the challenge treasury teams cited most often, by 49% of respondents. Smaller finance teams without a dedicated treasury function face the same problem with fewer people.

The source data is in more than one place. Bank balances, the general ledger, AR aging, and the payroll schedule often sit in different systems. If the runway spreadsheet is fed by manual exports, it is only as current as the last export.

What to track besides the headline number

A runway figure answers "how long." It does not answer "what changed" or "when is the tight point." Track these alongside it:

• Net burn trend. Three to six months of net burn, so a rising trend is visible before it shortens runway by a quarter.
• Burn by category. Payroll, vendors, software, facilities, debt service. If burn rises, you need to know which line moved.
• Collections and DSO. Days sales outstanding tells you whether cash in is slipping even when revenue is growing.
• The cash low point. Runway assumes an even burn, but cash rarely falls evenly. A payroll date, an annual insurance premium, or a loan payment can create a trough weeks before the average suggests. A 13-week cash flow view shows the lowest projected balance, which matters more for operating decisions than the month count.
• Committed but unpaid spend. Signed contracts, approved purchase orders, and accepted offers that have not hit the bank yet. They belong in the forward view even though they are not in the trailing average.

For context on why this matters: of U.S. private-sector establishments that opened in the year ending March 2014, the Bureau of Labor Statistics' establishment survival data shows 79.7% were still operating one year later and 50.8% after five years. The data does not record why businesses close, but it is a reminder that half of new establishments do not reach year five, and running out of cash is one of the ways that happens.

A tracking cadence that works

Runway tracking does not need to be daily. It needs to be regular and tied to the close.

Weekly (15 minutes): Check the bank balance against the 13-week projection. Confirm the projected low point is above your minimum cash threshold. Note any large receipts that are late or payments that came early. Our 13-week cash flow starter is a free template for this view.

Monthly (after close): Recalculate runway from closed books, not preliminary numbers. Update the three-month trailing net burn, compare it with the prior month, and explain any change over 5%. Re-run the gross-burn floor. If you close in QuickBooks, this is the point where the ledger, the bank and the runway figure should all agree. Our guide to month-end close covers how to make that close dependable.

Quarterly (with the board pack): Present runway as a range, not a single number. Show the trailing-average figure, the latest-month figure, the gross-burn floor, and the projected runway under your operating plan. Name the two or three assumptions that would change the answer most, such as the hiring plan, a large renewal, or a price change.

On trigger events: Recalculate immediately when something material happens: a funding round closes, a large customer churns or pays late, a major hire or layoff, a new debt facility, or a significant contract signs.

Setting thresholds and acting on them

Runway is only useful if a number triggers a decision. Agree in advance on thresholds with your CEO and board, for example:

• Above 18 months: operate to plan.
• 12 to 18 months: start fundraising or financing preparation, and review discretionary spend.
• Below 12 months: freeze non-critical hiring, renegotiate payment terms, and accelerate collections.
• Below 6 months: execute a defined cash-preservation plan.

The exact thresholds depend on how long your financing process usually takes and how predictable your revenue is. What matters is that they are written down before you need them, so the conversation at 11 months is about executing the plan, not debating whether there is a problem.

Runway tells you how much time you have. For how to forecast it forward with hiring plans and scenarios, see runway forecasting. For how to judge whether the cash you are burning is buying enough growth, see burn rate management.

Runway tracking checklist

• Calculate runway on net burn using a three-month trailing average, and show the latest month alongside it.
• Report the gross-burn floor so everyone sees how much runway depends on collections.
• Use only unrestricted cash in the numerator.
• Watch the projected cash low point in a 13-week view, not just the month count.
• Recalculate after every close and after any material event.
• Agree action thresholds with leadership before you need them.

Tech for CFO's RunwayWatch is a runway and burn tracker for QuickBooks Online users. In the meantime, our overview of cash flow tools for QuickBooks compares the options available today.