Cash Runway Formula: How to Calculate It, With Examples

The cash runway formula is cash on hand ÷ net monthly burn. That division is the easy part. The hard part is knowing which cash, which burn, and whether the number you get actually describes how long you'll survive — or just how long you'd survive if nothing changed, which never happens.

This page is the formula, the gross-vs-net distinction most founders get wrong, a real worked example using Lucid Motors' Q1 2026 numbers, and the benchmarks investors are using to judge runway in a tight 2026 funding market.

Want runway on your phone? Framework for iPhone & iPad ships a finance-metrics worksheet — drop in cash and burn, see runway and the thresholds below update live. Or start with the Runway and Burn Rate glossary entries.

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The cash runway formula

Cash runway (months) = Cash on hand / Net monthly burn

Net burn is cash going out minus cash coming in, in the same period. For a pre-revenue company, net burn equals gross burn — every dollar of spend is a dollar of depletion. For a revenue-generating company, collected cash offsets some of the spend, and runway stretches accordingly.

The single most common error is dividing by the wrong burn. There are two:

Burn type	Definition	Runway it produces
Gross burn	Total monthly cash outflow — payroll, cloud, marketing, rent, everything	Gross runway — the worst case, assumes zero revenue
Net burn	Gross burn minus cash revenue collected that month	Net runway — the realistic case used in board decks

Report both. Net runway is the number you plan around; gross runway is the number you stress-test against, because revenue can disappear faster than costs.

How to calculate cash runway (5 steps)

1. Take cash on hand, not "total assets." Use cash and liquid equivalents you can actually spend this quarter. Exclude restricted cash, receivables you haven't collected, and an undrawn credit line unless it's committed and accessible.
2. Sum gross monthly burn. Every cash outflow: fully-loaded payroll (including founders and execs), infrastructure, marketing, rent, software, taxes. One-time costs count toward depletion even if you label them "one-off."
3. Subtract cash revenue actually collected. Not GAAP revenue — cash. A SaaS company billing $120K annually upfront collects $120K in month one and $0 in months 2–12, even though it books $10K of revenue each month. Cash burn uses what landed in the bank.
4. Divide cash by net burn. That's net runway in months. Divide by gross burn for the worst-case gross runway.
5. Check the trend, not just the snapshot. Recompute burn for the last three months. If it's rising, your true runway is shorter than the latest single-month figure implies — see the worked example below for exactly this trap.

Worked example: Lucid Motors, Q1 2026

Most runway tutorials use a tidy hypothetical startup. Here is a real, public, current one — and it shows why the trend matters more than the snapshot.

In its Q1 2026 results, EV maker Lucid Group reported:

Metric	Q1 2026 value	Source
Liquidity at quarter-end	~$3.2B	Lucid IR
Cash burned in the quarter	~$1.44B	Yahoo Finance
Cash burned, same quarter prior year	~$589.9M	Yahoo Finance
Capital raised April 14, 2026	~$1.05B	PR Newswire

Run the formula. Convert the quarterly burn to monthly: $1.44B ÷ 3 ≈ $480M/month of net burn.

Cash runway = $3.2B / $480M per month ≈ 6.7 months

Roughly two quarters of cash at the Q1 pace. That is why Lucid announced a ~$1.05B raise on April 14 — $550M in convertible preferred from PIF affiliate Ayar, $300M in common stock, and a $200M investment from Uber. Pro forma, liquidity rises to ~$4.7B, which resets runway to:

Cash runway (pro forma) = $4.7B / $480M per month ≈ 9.8 months

Now the lesson the snapshot hides: a year earlier, Lucid burned $589.9M in the comparable quarter. Burn more than doubled year over year. If you'd calculated Lucid's runway off last year's burn rate, you'd have estimated more than twice the life it actually had. Runway computed on stale burn is the single most dangerous number on a founder's dashboard — and Lucid is the textbook case of why you recompute burn every quarter and read the direction, not just the level.

(Lucid is also a special case for a second reason, covered in "When the formula misleads" below: it's majority-backed by Saudi Arabia's Public Investment Fund, so its real survival question isn't the static formula — it's how long until the next sovereign injection.)

The Runway Triangle: three numbers, not one

Here's the synthesis that ties Framework's finance cluster together. A runway figure in months is necessary but not sufficient. To know whether that runway is real, read it as a triangle of three numbers — duration, efficiency, and timing:

Vertex	The number	Healthy in 2026	What it catches
Duration	Net runway in months	18+ (24–30 post-raise)	How long the cash lasts at current burn
Efficiency	Burn Multiple = net burn ÷ net new ARR	< 1.5	Whether the burn is buying durable growth
Timing	Does runway clear the fundraise cycle?	Runway > ~23 months	Whether you'll be raising from strength or desperation

A company can pass any one vertex and still die. Twenty-four months of runway with a Burn Multiple of 4.0 means you have time but you're setting money on fire — investors will see it. A best-in-class Burn Multiple with only 5 months of runway means you're efficient but about to run out before the next raise closes. The Runway Triangle fails when any single vertex is red, even if the other two are green — that's the diagnostic. Duration tells you if you survive; Efficiency tells you whether you deserve to; Timing tells you whether the market will let you.

This is why runway should never be reported as a lone number in a board deck. Pair it with the Burn Multiple (capital efficiency) and, at scale, the Rule of 40 (growth-plus-profit balance). The three are complementary reads, not substitutes.

2026 benchmarks: what counts as a good runway now

The canonical target used to be a flat 18 months. The 2026 market moved it:

Benchmark	2026 figure	Source
Expected post-raise runway	24–30 months	The VC Corner
Median fundraising cycle	~23 months	The VC Corner
Seed SaaS median monthly burn	~$80K	The VC Corner
Seed fintech median monthly burn	~$120K	The VC Corner
Startup failures from cash depletion	38%	CB Insights, via Brex
Survival edge of 12+ months runway	3.5× better odds vs. under 6 months	The VC Corner

The takeaway: because the median raise now takes ~23 months to come together, a runway under ~18 months puts you back in the market before your current round has had time to produce results. You raise from weakness, which is the worst time to raise.

When the cash runway formula misleads

The formula is a snapshot of a moving system. Don't trust it blindly in three cases:

• Burn is accelerating. The Lucid case. Last period's burn understates next period's, so dividing by the trailing number overstates runway. Fix: use a forward-looking burn forecast with named hires and their start dates, not the trailing average.
• A strategic backer can inject capital on demand. For a PIF-backed Lucid, a Microsoft-backed lab, or a corporate-venture-funded subsidiary, the static formula is almost irrelevant — the real question is "how long until the next injection, and on what terms?" The cash-÷-burn number describes the floor, not the plan.
• Revenue is ramping fast. If net burn is shrinking 10–15% a month because collections are climbing, this month's net runway understates your life — you may cross into cash-flow-positive before you'd hit zero. Model the burn curve, not a flat line.

In all three, the move is the same: replace the single trailing number with a 3-statement forecast, and read it next to the unit economics — because durable runway ultimately comes from each customer adding cash, not subtracting it.

Common cash runway mistakes

Mistake	Why it happens	Fix
Dividing by gross burn but calling it net runway	Confuses the two burn types	Subtract collected cash first; report both runways
Counting GAAP revenue as cash	Annual-billed SaaS books revenue it hasn't collected	Use cash actually in the bank
Using last single month's burn	One quiet month flatters the number	Average the trailing three; check the trend
Treating an undrawn credit line as cash	It looks like available money	Only count committed, accessible facilities
Reporting runway as one lone number	Hides efficiency and timing risk	Use the Runway Triangle — duration + Burn Multiple + raise-cycle fit

Related reading

Runway is the survival metric, but it's downstream of the inputs Framework's finance glossary covers in depth:

• Runway — the thresholds (18 / 12 / 6 months) and what founders do at each
• Burn Rate — gross vs net burn and the Burn Multiple in full
• Unit Economics — whether each customer extends or shortens runway
• Rule of 40 — the growth-plus-profit efficiency read at scale
• Payback Period — how fast CAC returns as cash, the lever that turns burn into runway

For prioritizing what to cut when runway tightens, the RICE scoring method is the standard tool for ranking which bets survive a budget cut.

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Run your numbers: Framework's iOS app keeps cash, burn, runway, and the Runway Triangle in one finance worksheet. Get it on the App Store.

Sources

• Lucid Group — "Lucid Announces First Quarter 2026 Financial Results"
• Lucid Investor Relations — Q1 2026 financial results
• Yahoo Finance — "Lucid Q1 results miss estimates; cash burn expected to continue"
• The VC Corner — "Startup Cash Runway Model 2026: Stay Funded Longer"
• Brex — "3 ways to extend your startup runway and reduce cash burn"