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How to Calculate Burn Rate and Runway

Calculate gross burn, net burn, and runway step by step, with a worked example and the most common mistakes founders make when estimating how many months of cash remain.

Updated 2026-06-29

Free calculators used in this guide

Burn Rate CalculatorBreak-Even CalculatorSmall Business Loan CalculatorCustomer Acquisition Cost Calculator

Overview

Burn rate and runway are the two numbers that determine how much time a pre-profitability startup has left before it must reach break-even or raise more capital. This article walks through exactly how to calculate gross burn, net burn, and runway from your own cash balance, expenses, and revenue — and the planning mistakes that most commonly lead founders to misjudge how much time they actually have.

This guide is for startup founders, finance teams, and early employees who need to understand cash runway well enough to plan hiring, spending, and fundraising timing with confidence.

What You Need

Before calculating burn rate and runway, gather:

  • Current cash balance — the actual amount in your bank accounts today
  • Total monthly operating expenses — payroll, rent, software, marketing, and all other recurring costs
  • Total monthly revenue — recurring and non-recurring combined, for the burn calculation
  • Any known upcoming one-time expenses or revenue events that will affect the next few months

Steps

Step 1: Calculate gross burn rate

Gross Burn Rate = Total Monthly Operating Expenses

This is your full cost structure before accounting for any revenue. It shows the absolute scale of spending regardless of how much the business is bringing in.

Step 2: Calculate net burn rate

Net Burn Rate = Total Monthly Operating Expenses − Total Monthly Revenue

Net burn is the figure that actually matters for runway, because it reflects the real rate at which cash is leaving the business after revenue is accounted for.

Metric Value
Cash balance $1,200,000
Monthly operating expenses (gross burn) $150,000
Monthly revenue $70,000
Net burn $80,000/month

Step 3: Calculate runway in months

Runway (months) = Current Cash Balance / Net Burn Rate

Using the example above: $1,200,000 / $80,000 = 15 months of runway

Step 4: Stress-test runway against rising expenses

Model a realistic worst case — for example, planned hiring that increases monthly expenses to $180,000 while revenue holds flat:

New net burn = $180,000 − $70,000 = $110,000/month

New runway = $1,200,000 / $110,000 ≈ 10.9 months

This single hiring decision shrinks runway by more than 4 months — always recalculate runway under planned future spending, not just the current month's figures.

Step 5: Calculate the burn multiple (optional, for growth-stage companies)

Burn Multiple = Net Burn / Net New ARR Added

If the company above adds $40,000 in net new ARR this month while burning $80,000: Burn Multiple = 80,000 / 40,000 = 2.0 — meaning it costs $2 of burn to generate $1 of new recurring revenue. A burn multiple under 1 to 1.5 is generally considered efficient for growth-stage SaaS companies.

Use the Burn Rate calculator to run your own numbers and model different expense and revenue scenarios.

Common Mistakes to Avoid

  • Using gross burn instead of net burn for runway — this overstates how fast cash is actually depleting and understates true runway, especially for companies with meaningful revenue.
  • Treating runway as a fixed number — runway shrinks non-linearly as expenses rise; recalculate monthly, not just at the start of the year.
  • Letting one-time expenses distort the monthly figure — a single large annual insurance payment or legal settlement can spike one month's burn; use a normalised or trailing-average burn rate for planning.
  • Waiting until runway is under 3-6 months to start fundraising — this weakens negotiating leverage significantly; most experienced founders begin raising when 6-9 months of runway remain.

Formula & Methodology

Gross Burn Rate = Total Monthly Operating Expenses

Net Burn Rate = Total Monthly Operating Expenses − Total Monthly Revenue

Runway (months) = Current Cash Balance / Net Burn Rate

Burn Multiple = Net Burn / Net New ARR Added

For more conservative planning, calculate runway using a 3-month trailing average of net burn rather than the most recent single month, which smooths out seasonal or one-time spikes and gives a more reliable estimate of sustainable spending trajectory.

Key Terms

  • Burn Rate — the rate at which a company spends its cash reserves before reaching profitability
  • ARR — Annual Recurring Revenue; MRR annualised, used to calculate the burn multiple
  • MRR — Monthly Recurring Revenue; the predictable monthly revenue base a SaaS company collects
  • Working Capital — the cash and liquid assets available to fund day-to-day operations
  • CAC — Customer Acquisition Cost; a major driver of burn rate at growth-stage companies

Frequently Asked Questions

Gross burn is total monthly operating expenses, regardless of revenue. Net burn subtracts monthly revenue from gross burn — it's the actual cash draining from the bank account each month. A company with $150,000 in expenses and $70,000 in revenue has a gross burn of $150,000 but a net burn of only $80,000. Runway should always be calculated using net burn, not gross burn.
Most investors expect founders to maintain at least 12-18 months of runway and to start the next fundraise when 6-9 months remain — not when the bank account is nearly empty. Running low on cash before raising significantly weakens negotiating leverage and can force founders to accept worse terms or a lower valuation than the business otherwise deserves.
For runway planning, it's more useful to calculate a normalised burn rate that smooths out one-time items (a large equipment purchase, a legal settlement, an annual insurance premium) alongside the raw monthly figure. Including a one-time spike in burn rate without adjustment can make runway look artificially short for that single month and mislead near-term planning decisions.
Burn multiple = Net Burn / Net New ARR Added. It measures capital efficiency — how much cash a company burns to generate each new dollar of recurring revenue. A burn multiple under 1 (more than $1 of new ARR per $1 burned) is considered highly efficient; above 2-3 raises questions about whether growth is being bought rather than earned. Two companies with identical burn rates can have very different burn multiples depending on how much ARR that spending produces.
Hiring is usually the single largest driver of rising burn rate, since salaries, benefits, and payroll taxes are recurring monthly costs that compound across a growing headcount. A founder planning to add 5 engineers at a fully loaded cost of $15,000/month each adds $75,000 to monthly gross burn — recalculate runway under this future expense scenario before committing to a hiring plan, not just under the current run-rate.
As runway shortens, startups typically face three levers: cut costs (reduce headcount or pause non-essential spending) to extend runway, accelerate revenue growth to reduce net burn, or raise additional financing through equity, venture debt, or a bridge round. Combining levers — for example, cutting burn by 20% while closing a handful of large deals — is often more effective than relying on any single lever alone.
No — burn rate must be evaluated relative to growth and runway, not in isolation. A company burning $200,000/month while growing ARR by $50,000/month and holding 24 months of runway is in a fundamentally different position than a company burning the same $200,000/month with flat revenue and 6 months of runway. Context (growth rate, funding stage, market conditions) determines whether a given burn rate is sustainable.
Monthly, at minimum, and ideally as part of a standing finance review. Burn rate and runway are not static — rising expenses (hiring, marketing spend increases), revenue growth or decline, and one-time events all shift the numbers. Many finance teams maintain a rolling 3-month average burn rate alongside the latest single-month figure to separate noise from a genuine trend.
Burn rate is a cash metric — actual money leaving the bank account. Net loss is an accounting metric that includes non-cash items like depreciation, amortisation, and stock-based compensation. A company can report a large net loss while burning relatively little cash (if losses are driven by non-cash charges), or the reverse. Always calculate burn rate from cash flow statements or bank balance changes, not from the income statement's bottom line.
Burn rate specifically describes a company spending down its cash reserves faster than it generates revenue — once a company is consistently cash-flow positive, it no longer has a 'burn rate' in the traditional startup sense, since it's generating cash rather than consuming it. Some growth-stage companies intentionally choose to operate at a controlled burn even after reaching profitability, reinvesting cash into growth rather than banking it — in that case, the 'burn' is a deliberate strategic choice rather than a survival risk.

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