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Calculation details
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Use this result
Share the current inputs or ask ChatGPT to explain the calculation in context.
What does this calculator estimate?
A cash flow runway calculator shows how long your cash lasts. Enter starting cash, monthly revenue and expenses (with optional growth rates) to see your runway and depletion month.
- Burn = expenses − revenue
- Runway = cash ÷ monthly burn
- The #1 metric for startups and small businesses
Why runway matters
Runway is how many months you can operate before cash runs out — the core survival metric for startups and seasonal businesses. Knowing it forces honest planning: cut burn, grow revenue, or raise capital before the clock hits zero.
Limitations to watch for
The estimate assumes predictable monthly flows; real revenue and expenses swing. Growth rates are projections, not promises. The tool projects depletion but doesn't model irregular expenses (annual insurance, taxes) or funding events.
How to use it in practice
Track starting cash and your realistic monthly revenue/expense. Re-run monthly as numbers change. If runway drops below 6 months, act: cut burn, accelerate revenue, or raise funds. Use the break-even month to know when cash flow turns positive.
- Enter starting cash, monthly revenue, and expenses.
- Optionally enter growth rates and the horizon.
- Read your runway, depletion month, and break-even month.
What runway measures
Runway is how long a business can operate before cash runs out: current cash ÷ monthly burn. $60,000 cash with a $15,000 monthly burn gives 4 months of runway. Startups and agencies track it as the primary survival metric.
Gross vs. net burn
Gross burn is total monthly spending; net burn subtracts revenue. A company spending $50,000 with $35,000 revenue has $15,000 net burn — runway extends from the gross number to the net number. The calculator uses net burn so the runway reflects reality.
The runway cliff
At 6 months of runway, hiring freezes; at 3, spending reviews; at 1, emergency. The calculator's projection makes the cliff date concrete — a company with 4 months of runway knows the exact month decisions must land.
A worked example
$80,000 cash, $20,000 monthly net burn: 4 months runway — cash out by the end of month 4. Cutting burn to $15,000 extends it to 5.3 months; adding $10,000 monthly revenue extends it to 8. The calculator shows each lever's effect on the date.
Planning beyond the runway
Runway funds the race to revenue or the next raise. The calculator shows the number; the plan is the milestones that must clear before the cliff — product, launch, or funding round.
How this calculator works
Formula
Monthly burn = monthly expenses − monthly revenue. Runway = starting cash ÷ burn. The tool also projects depletion month and break-even month with optional revenue/expense growth.
Worked example
$50,000 cash with $10,000 revenue and $12,000 expenses: burn = $2,000/month, so runway ≈ 25 months.
Assumptions to verify
- Monthly revenue and expenses are steady (or follow the entered growth).
- The horizon is up to 120 months.
- No funding events or irregular expenses are modeled.
Frequently asked questions
What is cash runway?
How many months your business can operate before cash runs out, at your current burn rate.
How do I calculate it?
Burn = monthly expenses − monthly revenue; runway = cash ÷ burn. $50,000 ÷ $2,000 = 25 months.
What is the burn rate?
Net cash consumed per month — expenses minus revenue. Negative burn (profit) extends runway indefinitely.
How much runway should I have?
6–12 months is a common safety target for startups; less than 6 is action territory.
What can I do to extend runway?
Cut non-essential costs, raise prices, accelerate collections, reduce inventory, or raise capital.
What is the break-even month?
The month when revenue first covers expenses — cash flow turns positive and runway stops shrinking.
Is the projection accurate?
It's as accurate as your inputs. Re-run it monthly with real numbers and treat growth assumptions as scenarios.
How do I calculate runway?
Current cash ÷ monthly net burn (spending minus revenue).
What is the difference between gross and net burn?
Gross is total spending; net subtracts revenue — runway uses net.
How much runway is healthy?
12+ months is comfortable; under 6 months triggers immediate cost and revenue actions.
How do I extend runway?
Cut burn, raise revenue, or raise capital — the calculator shows each lever's effect.
Cite this tool
BoringToolsKit. “Cash-Flow Runway Calculator.” boringtoolskit.com/cash-flow-runway-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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