What Is Cash Runway?
Cash runway is the number of months (or weeks) your business can continue operating before it runs out of cash — assuming no changes to revenue or spending. It's the single most important number for any business that isn't yet consistently profitable, and one of the most important even for those that are.
Think of it as a countdown timer. When your runway hits zero, the lights go off. Every business decision you make either extends or shortens that timer — hiring someone, signing a new lease, losing a client, landing a big contract.
Unlike profit margins or revenue growth, runway is unambiguous. There's no creative accounting. Either you have the cash to pay your bills next month, or you don't.
Why runway matters more than profit: A business can be profitable on paper and still die. If your clients pay net-60 but your payroll hits every two weeks, your income statement looks healthy while your bank account bleeds dry. Runway tells you the truth your P&L won't.
The Cash Runway Formula
The core formula is straightforward:
Where:
- Cash Balance = Total cash and cash equivalents available right now (checking + savings + money market accounts — don't count receivables)
- Monthly Burn Rate = Net cash leaving your business each month (total expenses minus total revenue, if you're burning cash). For profitable months, burn rate is negative — meaning your runway is technically infinite (but still worth tracking)
Net burn vs. gross burn
This distinction matters more than most founders realize:
- Gross burn rate = Total monthly expenses, regardless of revenue. If you spend $50,000/month and earn $30,000/month, your gross burn is $50,000.
- Net burn rate = Total expenses minus total revenue. In the same example, net burn is $20,000/month.
Always use net burn rate for runway calculations. Gross burn is useful for understanding your cost structure, but net burn reflects what's actually happening to your bank account. If you use gross burn, you'll dramatically underestimate your runway and make panicked decisions you don't need to make.
For a deeper look at burn rate mechanics, see our complete burn rate guide.
Runway Examples by Business Stage
Runway means different things depending on where your business is. Here are four real-world scenarios:
🚀 Pre-Revenue Startup
Cash in bank: $150,000 (seed funding)
Monthly burn: $25,000 (2 founders + contractor + SaaS tools + rent)
Monthly revenue: $0
Runway = $150,000 ÷ $25,000 = 6 months
📈 Growing SaaS Company
Cash in bank: $400,000
Monthly expenses: $80,000 (team of 8 + infrastructure + marketing)
Monthly revenue: $55,000 (MRR, growing 10%/month)
Net burn: $80,000 - $55,000 = $25,000/month
Runway = $400,000 ÷ $25,000 = 16 months
🏗️ Seasonal Contractor
Cash in bank (entering winter): $85,000
Monthly expenses (winter): $22,000 (insurance, equipment storage, minimal crew)
Monthly revenue (winter): $5,000 (small interior jobs)
Net burn: $22,000 - $5,000 = $17,000/month
Runway = $85,000 ÷ $17,000 = 5 months (needs to survive until spring)
🏪 Profitable Small Business
Cash in bank: $120,000
Monthly expenses: $45,000
Monthly revenue: $62,000
Net burn: -$17,000 (generating cash)
Runway = Infinite (cash-flow positive) — but $120K ÷ $45K = 2.7 months of expenses as a safety buffer
How Much Runway Do You Need?
There's no universal answer, but here are the benchmarks that experienced operators and investors use:
Context matters. A SaaS company with 90% gross margins and growing 15%/month is fine at 6 months of runway. A restaurant with 8% margins in a competitive market probably needs 9–12 months to feel truly safe.
Common Mistakes That Shorten Runway
Most businesses don't run out of cash because of one catastrophic event. They die from a series of small miscalculations:
1. Counting receivables as cash
If a client owes you $40,000 but hasn't paid yet, that's not cash. It's a promise. Your landlord, your employees, and your vendors don't accept promises. Only count money that's in your bank account today when calculating runway.
2. Using average burn rate during variable months
If you spent $30K in January and $60K in March (because of a quarterly insurance payment + annual software renewal), your "average" of $45K is misleading. Build your forecast month-by-month, accounting for lumpy expenses: quarterly taxes, annual renewals, bonus payments, inventory restocks.
3. Ignoring revenue variability
Don't assume next month's revenue will match this month's. If you have seasonal patterns, factor them in. If you're losing clients, project declining revenue. The most dangerous runway calculation is one built on optimistic revenue assumptions.
4. Forgetting about one-time expenses
Equipment purchases, security deposits, legal fees, conference travel — these don't show up in your recurring expenses but they drain cash fast. Build a "known upcoming" list and subtract it from your available balance.
5. Not recalculating after major changes
Hired two people? Lost your biggest client? Signed a new office lease? Your old runway number is now fiction. Recalculate every time your cost structure or revenue changes materially.
The optimism trap: Founders and SMB owners systematically overestimate future revenue and underestimate future costs. When in doubt, use conservative estimates. Build your plan around the downside case — then be pleasantly surprised if the base case plays out.
When to Worry About Your Runway
Your runway number alone doesn't tell the full story. Here's when to escalate from monitoring to action:
- Runway is trending down — It's not just the absolute number; it's the direction. If you had 9 months of runway in January and 6 months in March, you're losing ground fast. The rate of change matters more than the current number.
- You're 6+ weeks from break-even — If you're a growing business that's almost profitable, dropping below 6 months of runway while still burning means you need to either accelerate to profitability or find additional capital.
- Your largest client represents >20% of revenue — If they leave, your burn rate spikes overnight. Calculate your runway with and without that client.
- You have a debt payment cliff — SBA loans, revenue-based financing, and lines of credit have due dates. If a large payment is due in 4 months and you have 5 months of runway, you effectively have 1 month.
- Your industry is in a downturn — External factors reduce the reliability of your revenue projections. Add a 20–30% haircut to revenue estimates during uncertain periods.
How to Extend Your Cash Runway
When runway gets tight, you have exactly two levers: bring in more cash, or spend less. Here's what actually works:
Revenue-side actions (bring cash in faster)
- Tighten payment terms: Move from net-60 to net-30. Offer 2% early-payment discounts. Start sending reminders at day 15, not day 45.
- Invoice faster: If you bill at month-end, switch to billing at project milestones. Get cash flowing before the work is fully complete.
- Sell annual plans: Convert monthly subscriptions to annual prepay with a 15–20% discount. You give up some margin but gain 11 months of runway per conversion.
- Raise prices: If your last price increase was 18+ months ago, you're probably underpriced. Even a 10% increase across your client base adds months of runway.
Cost-side actions (slow the burn)
- Audit your SaaS stack: The average SMB spends $1,200–$2,400/month on software. Cancel anything with fewer than 3 active users or without a clear ROI.
- Renegotiate vendor contracts: Landlords, insurance brokers, and long-term vendors will often negotiate when the alternative is losing you as a customer. Ask for 60-day payment extensions during cash-tight months.
- Pause non-essential hiring: Every new hire adds $5,000–$15,000/month in fully-loaded cost. If runway is under 6 months, wait until you can see 9+ months before adding headcount.
- Defer large capital expenditures: That new equipment or office renovation can wait. Lease instead of buy when possible.
The 3-month rule: Any cost-cutting decision should show up in your burn rate within 30–90 days. If it doesn't, it's not real savings — it's just a plan. Track whether your actual burn rate drops after each change.
Stop Calculating Runway in Spreadsheets
Manually calculating runway from bank statements and spreadsheets works — until it doesn't. The problem isn't the math (it's simple). The problem is consistency. When things get busy, the spreadsheet doesn't get updated. When things get scary, the numbers get massaged.
CashScope automates runway tracking by connecting directly to your QuickBooks or Xero account. It pulls your real cash balances and real expenses — not estimates — and calculates your runway every week.
Every Friday, you get a plain-English report in your inbox:
- Your current cash runway in months
- How runway changed from last week and why
- Whether your burn rate is trending up or down
- Specific actions to consider if runway is tightening
- 60–90 day forward projection based on actual patterns
No dashboards to check. No spreadsheets to update. Just the truth about your cash position, delivered before the weekend when you actually have time to think about it.