SaaS Burn Rate & Cash Runway: The Complete Guide (2026)

How to Calculate Cash Runway

The basic formula for Cash Runway is:

Cash Runway = (Cash + Cash Equivalents) ÷ Monthly Net BurnNet burn = costs − revenue

Example:

• Current Cash and Cash Equivalents: $1,000,000
• Monthly Net Burn: $100,000

Cash Runway = $1,000,000 ÷ $100,000 = 10 months

You can also cross-check your own numbers with our free cash runway calculator.

Gross Burn vs. Net Burn

Which burn figure you divide by changes the answer, so it pays to know the difference:

Worked contrast: a startup with $750,000 in the bank spends $80,000/month and earns $50,000/month.

Net runway = $750,000 ÷ ($80,000 − $50,000) = 25 monthsNet burn $30,000/mo

Gross runway = $750,000 ÷ $80,000 = 9.4 monthsIf revenue dropped to zero

Net burn shows the likely path; gross burn shows how quickly things unravel if revenue disappears. Investors usually look at both.

How Much Runway Does a Startup Need? (2026 Benchmarks)

Runway targets rise with stage, and the old 12-month rule has stretched. Know your target before you run out. Here are 2026 median targets by stage:

These are targets to raise to, not floors to drain to. Raise more in slow funding markets, and remember the goal is runway to your next fundable milestone, not just runway to zero. Run the "default alive" test (below) on your numbers to know where you actually stand.

Burn Multiple: Is Your Burn Buying Growth?

Runway tells you how long you last; the burn multiple tells you whether the burn is buying growth. Popularized by David Sacks of Craft Ventures, it divides net burn by the new recurring revenue it produced:

Net Burn ÷ Net New ARR = Burn MultipleLower is better: how many dollars burned per $1 of new ARR

Sacks' scale for efficiency:

Early-stage reality runs higher. Seed-stage companies typically sit at 2.5-3.4x, with above 3x at seed a risk flag that capital is not buying enough new revenue. The burn multiple is the cleanest one-number read on capital efficiency, which is exactly what investors reward in the current market. To dive deeper, see the burn multiple explained and SaaS unit economics.

Default Alive vs Default Dead

Paul Graham's framing (in his essay "Default Alive or Default Dead?") is the question every founder should be able to answer: at your current growth rate and spending, will you reach profitability before the money runs out? If yes, you're default alive; if no, default dead. The point isn't that default-dead is fatal, it's that founders often don't know which they are until it's late. In 2026, investors increasingly fund default-alive companies to accelerate, not default-dead ones to survive. Run the number early and honestly, and if you're default dead, know exactly which lever (growth or burn) closes the gap.

When Should You Raise Based on Runway?

Two rules that seem to conflict but don't:

(a) Keep 18-24 months of runway at close. This is the target to raise to, enough buffer to hit your next milestone and still have time to raise again if needed, since a round itself takes 3-6 months to close.

(b) Start raising with 9-12 months of runway left. Pre-seed rounds close ~2 months, seed ~3 months, Series A ~4 months. Begin conversations when your forecast shows 9-12 months left, so you close before dropping under the danger zone (6 months or less). Less than 6 months of runway puts you in a weak negotiating position.

The reconciliation: raise when forecast shows 9-12 months left, close with 6-18 months remaining. Know your target before you're desperate. See SaaS fundraising guide for the full raise process and cash flow forecasting for the method to predict when you'll hit that runway target.

How to Extend Your Runway / Reduce Burn

You have two levers:

Reduce burn rate:

• Cut non-essential costs
• Renegotiate vendor and hosting contracts
• Slow hiring and headcount growth
• Delay expansion plans

Increase cash:

• Accelerate revenue (discounts for annual upfront, new sales).
• Collect receivables faster (reduce AR days)
• Raise additional funding
• Sell non-core assets

Runway is an output of your whole financial model. The fastest way to extend it sustainably is to improve the drivers underneath, especially your unit economics. Adlega calculates your runway, gross burn, and net burn from your revenue and cost assumptions, and shows a cash-out chart so you can see the raise-or-cut decision months ahead. Its AI CFO answers the follow-up question directly, why burn moved in a given month, with the working shown. Model a slice first with the free runway calculator or dive into the full P&L waterfall.

Common Cash Runway Mistakes

• Using gross burn when net burn matters. Gross burn shows worst-case if revenue drops to zero, but net burn is your realistic path. Both are worth monitoring, but runway decisions use net.
• Ignoring seasonality and lumpy outflows. Payroll is monthly, but taxes, insurance, and bonuses hit in chunks. Forecast actual timing, not just monthly averages.
• Treating runway as static. Your forecast runway changes every month as revenue grows (or shrinks) and burn changes. Update it weekly or monthly, don't run on an old number.
• Raising too late. By the time you have 3 months of runway, you're in an emergency. Start conversations at 9-12 months left.
• Not knowing if you are default alive. Paul Graham's question - will you hit profitability before you run out of cash at your current rate - is the single most important one. Know the answer and which lever moves it.