TL;DR
Cash runway = cash and cash equivalents ÷ monthly net burn. It is the conservative floor on survival time — how long you last if no new revenue arrives and burn stays constant. Venture-backed companies should target 18+ months. Below 12 months, fundraising should already be underway. Unlike dynamic runway models, cash runway uses only liquid assets — no receivables, credit lines, or revenue projections.
What is cash runway?
Cash runway (also called cash-on-hand runway or cash survival period) is the number of months a company can continue operating using only the cash and cash equivalents currently in the bank, divided by the monthly net burn rate. It is the most conservative measure of financial survivability — it assumes no new revenue, no additional fundraising, and no burn reduction.
Cash runway differs from general runway calculations that include revenue projections or model burn changes over time. Cash runway is a static snapshot: what you have today divided by what you spend today. This makes it the standard reference point for investor due diligence and board-level risk assessment — everyone can agree on it because it requires no assumptions.
For COOs and founders at B2B SaaS companies ($3–30M ARR), cash runway is distinct from working capital. Working capital includes accounts receivable and other current assets. Cash runway only counts liquid, immediately accessible funds — checking accounts, money market accounts, and short-term treasury instruments. A company with $2M in accounts receivable and $400K in cash has $400K of cash runway, not $2.4M.
The standard fundraising heuristic — raise when you have 18 months of runway — refers specifically to cash runway. The logic: a Series A or Series B typically takes 4–6 months from first pitch to wire. Add 2 months of process preparation and 3 months of buffer for a delayed close, and the optimal fundraise initiation point is when cash runway hits 18 months.
Why cash runway matters for operators
Cash runway is the metric that converts all other financial metrics into a decision clock. EBITDA, gross margin, and burn multiple tell you how efficiently the business operates. Cash runway tells you how long you have to fix the ones that are wrong.
The asymmetry of running out of cash is extreme. Companies that drop below 3 months of cash runway lose negotiating leverage on every front simultaneously: fundraising terms worsen, acquirer interest drops, key employee retention becomes difficult, and vendor contracts become harder to renegotiate. Operators who track cash runway monthly preserve optionality. Operators who discover a cash problem in a board meeting have already lost it.
A mid-market SaaS company with $800K in cash and $120K net burn has 6.7 months of cash runway. At $120K/month, that company cannot afford a slow fundraise, an unexpectedly large payroll month, or a customer payment that arrives 30 days late. Cash runway makes these risks concrete and actionable.
Cash runway formula
Cash Runway (months) = Cash and Cash Equivalents ÷ Monthly Net Burn Monthly Net Burn = Gross Burn - Cash Revenue Collected Example: Cash in bank (checking + money market): $1,820,000 Monthly gross burn: $290,000 Monthly revenue collected (cash basis): $134,000 Monthly net burn: $290,000 - $134,000 = $156,000 Cash Runway = $1,820,000 ÷ $156,000 = 11.7 months Conservative floor (gross burn only): Cash Runway = $1,820,000 ÷ $290,000 = 6.3 months (Use this when revenue is uncertain or customer concentration is high)
- Cash and cash equivalents: Checking accounts, savings accounts, money market funds, and U.S. Treasury bills with <90-day maturity. Excludes accounts receivable, prepaid expenses, inventory, and credit line availability.
- Monthly net burn: Gross cash outflows minus cash revenue actually collected in the period. Use cash receipts, not accrued revenue. A $150K MRR SaaS company that bills annually may collect $0 in cash in 11 of 12 months — use actual collections, not ARR÷12.
- Gross burn floor: Calculate cash runway against gross burn as a stress test. If gross-burn-only runway drops below 3 months, the company cannot survive even a temporary revenue interruption.
If the company has an undrawn credit line or committed equity commitment, note these as "additional available liquidity" separately — they are not cash, but they extend the real survival window if accessible. Never include undrawn credit in the primary cash runway calculation.
Cash runway benchmarks by stage
How cash runway targets and warning thresholds vary by company stage.
| Stage | Target Cash Runway | Start Fundraising | Warning Zone | Action if in warning |
|---|---|---|---|---|
| Pre-seed / seed | 12–18 months | At 15 months | Below 9 months | Pause non-essential hiring; initiate bridge or seed extension immediately |
| Series A ($1–5M ARR) | 18–24 months | At 18 months | Below 12 months | Begin investor outreach immediately; accelerate revenue initiatives |
| Series B ($5–20M ARR) | 18–24 months | At 18 months | Below 12 months | Dual-track: cost reductions + active fundraise; prioritize existing investors |
| Growth ($20M+ ARR) | 12–18 months | At 15 months | Below 9 months | Consider bridge from existing investors; explore debt financing options |
| Profitable / post-burn | 6–12 months operating buffer | No fundraise needed | Below 3 months | Emergency: revenue acceleration or immediate cost restructuring |
Sources: Y Combinator guidance; a16z portfolio benchmarks; Bessemer portfolio operator data. Thresholds reflect cash runway targets for typical VC-backed B2B SaaS companies.
Common mistakes when calculating cash runway
1. Including accounts receivable in cash
Accounts receivable represents money owed, not money available. A company with $500K in outstanding invoices and $300K in the bank has $300K of cash runway — not $800K. Receivables aged past 60 days are particularly suspect. Treat only cleared, liquid bank balances as cash for runway purposes.
2. Using ARR/12 instead of actual monthly cash receipts
Companies with annual billing plans receive cash in large lumps — often once or twice per year. Using MRR or ARR/12 to estimate monthly cash inflows dramatically overstates liquidity in months when no payments arrive. Pull actual bank deposits for the prior 3 months and average them for the net burn calculation.
3. Not adjusting for committed future expenditures
Existing cash runway calculations assume current burn continues. If the hiring plan adds $80K/month in headcount over the next 90 days, that burn isn't in last month's numbers — but it will reduce actual runway by 15–25%. Model runway forward using the planned burn schedule, not just historical burn.
4. Counting an undrawn credit line as cash
A $500K credit line that isn't drawn is not $500K in cash. Credit facilities can be withdrawn by lenders during financial stress — precisely when you need them most. Include them as a secondary note on liquidity, but never fold them into the primary cash runway calculation.
5. Not updating cash runway after major events
Cash runway changes every time the bank balance changes significantly or burn shifts materially. A single large payroll month, an unexpected infrastructure spend, or a delayed customer payment can compress runway by 1–2 months. Recalculate monthly, and recalculate immediately after any non-routine cash event.
How Fairview tracks cash runway automatically
Fairview's Operating Dashboard connects to QuickBooks, Xero, and your bank feeds to calculate cash runway in real time — using actual cash balances and actual monthly cash receipts, not accrual accounting figures or ARR estimates.
When cash runway drops through a threshold you define, the Next-Best Action Engine surfaces the alert with context: "Cash runway dropped to 13.2 months. Net burn increased $22K MoM due to payroll additions. At current trajectory, runway hits 12 months in 6 weeks. Recommend initiating investor conversations this quarter." The Forecast Confidence Engine models forward cash runway under three scenarios: current burn flat, burn at hiring-plan rate, and stress-test (gross burn only).
Cash runway vs runway
Cash runway is the static floor. Runway (in a dynamic model) projects forward based on the hiring plan, revenue growth trajectory, and expected burn evolution. Both numbers matter: cash runway for conservative risk assessment, dynamic runway for planning.
| Cash Runway | Dynamic Runway | |
|---|---|---|
| Burn assumption | Current net burn held constant | Models planned hiring, revenue growth, seasonal changes |
| Revenue assumption | Current cash collections held constant | Projected growth based on pipeline and retention |
| When to use | Investor conversations, board risk assessment, stress-test | Internal planning, hiring decisions, fundraise timing |
| Risk of error | Overconservative if growth is real | Overoptimistic if growth projections miss |
| Data required | Bank balance + last month's cash receipts | Full financial model with monthly cash flow projections |
At a glance
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Frequently asked questions
What is cash runway in simple terms?
Cash runway answers: if nothing changes — no new revenue, no cost cuts, no new funding — how many months can the business survive? Divide the cash currently in your bank account by the amount of cash you spend each month (net of revenue collected). The result is your cash runway in months. It is the most conservative view of financial survival.
How much cash runway should a startup maintain?
Venture-backed startups should maintain 18+ months of cash runway as a standard target. The rule exists because raising a round typically takes 4–6 months from first meeting to funds received — and founders who start raising with less than 12 months of cash runway negotiate from weakness. Below 9 months, options narrow significantly. Below 6 months, the business is in genuine existential risk unless cash is extended through a bridge or immediate cost restructuring.
Is cash runway the same as burn rate?
No. Burn rate is the speed at which you are consuming cash — typically expressed as monthly net burn in dollars. Cash runway is the duration — how many months remain at that burn rate. They are related: cash runway = cash ÷ burn rate. Burn rate is the velocity; cash runway is the time remaining. Both matter, but for board-level and investor communication, cash runway is usually the primary metric.
How do you extend cash runway without raising money?
Four mechanisms: (1) Reduce gross burn — pause or cut discretionary spend (non-essential SaaS tools, marketing channels with poor payback, deferred hires); (2) Accelerate cash collection — move customers to annual billing upfront, tighten payment terms from net-30 to net-10; (3) Improve net revenue retention — reducing churn directly reduces net burn because less revenue walks out; (4) Pursue revenue mix changes that improve contribution margin and cash conversion.
What should I include and exclude from the cash calculation?
Include: checking accounts, savings accounts, money market funds, U.S. Treasury bills with maturity under 90 days. Exclude: accounts receivable (not yet collected), undrawn credit lines (not guaranteed), prepaid expenses (spent but not consumed), and restricted cash held as security deposits or escrow. The goal is the number that would appear in the bank tomorrow if the business stopped all activity — liquid and immediately available.
Sources
- Y Combinator: Default Alive or Default Dead — Paul Graham
- a16z: How to Think About Burn Rate and Runway
- Bessemer Venture Partners State of the Cloud 2025 — portfolio operator benchmarks
Fairview is an operating intelligence platform that tracks cash runway in real time from live bank feeds — and alerts operators before the fundraise window closes. Start your free trial →
Siddharth Gangal is the founder of Fairview. He built live cash runway monitoring after watching founders learn their real runway for the first time in a board meeting — always at least two months later than they should have.
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