Startup Runway Calculator: Find Your Burn Rate and Months of Cash Left

Startup runway measures exactly how many months your business can continue operating before running completely out of cash. By comparing available cash reserves with your monthly net burn rate and projected revenue growth, this tool identifies your zero-cash date, tracks your trajectory toward operational break-even, and helps model your next fundraising round.

🎯 Who It's For:
  • Early-stage and venture-backed startup founders
  • Chief Financial Officers and corporate finance directors
  • Operators preparing headcount expansions or upcoming funding rounds
💡 Why Use It:
  • Accurately project cash depletion dates before reaching critical thresholds
  • Model the impact of monthly revenue expansion rates on cash longevity
  • Determine precise capital injection requirements for your next equity round
Fox Business Markets · Startup Runway Calculator
Currency:
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Monthly expenses include salaries, rent, software, and everything else you spend. Add a revenue growth rate to see whether you reach break-even before cash runs out. Expenses are assumed to stay the same.
Runway
Months of cash left
16.8 months
Net burn rate
Cash you lose this month
$40,000
Cash runs out
February 2028
Break-even
After cash runs out
Month 24
Cash balance by month
Now Month 17
With $500,000 in the bank and a net burn of $40,000 a month, your cash lasts about 16.8 months, until around February 2028. At 5% monthly revenue growth, you'd reach break-even in month 24, but your cash runs out first, so you'll need more funding or lower costs to get there.
For educational purposes only. Results are simple estimates based on the numbers you enter. Real cash flow changes month to month, so update your numbers often. Not financial advice.

How to Use the Startup Runway Calculator

Follow these structured steps to evaluate your burn rate, project cash runway, and map upcoming fundraising timelines:

  1. Select Currency: Choose your operational currency (USD, GBP, EUR, CAD, or AUD) from the currency selector.
  2. Cash in the Bank: Enter your total current liquid cash reserves, checking balances, and money market funds.
  3. Monthly Expenses: Enter your total monthly operating costs (payroll, contractor fees, cloud infrastructure, office rent, and SaaS subscriptions).
  4. Monthly Revenue: Enter your current baseline recurring revenue or cash collections.
  5. Revenue Growth per Month: Enter your historical or target month-over-month percentage revenue growth rate to model compounding expansion.
  6. Plan Your Next Raise: Toggle to the raise planner tab to determine how much capital to target based on your projected post-raise expense budget.

Core Formulas and Mathematical Methodology

Runway modeling evaluates how rapidly operational expenditures consume liquid capital reserves. The engine incorporates three primary financial equations:

1. Net Burn Rate Formula

Net Burn Rate = Total Monthly Expenses (Gross Burn) - Total Monthly Revenue

2. Baseline Static Runway Formula

Runway (Months) = Total Liquid Cash Reserves ÷ Net Monthly Burn Rate

3. Compounded Growth Cash Balance Simulation

Cash (Month n) = Cash (Month n-1) - [ Monthly Expenses - (Revenue × (1 + Growth Rate)^n) ]

4. Target Raise Round Sizing

Target Round Size = (Desired Runway Months + Contingency Buffer Months) × Projected Monthly Burn

Fully Worked Numerical Example

Consider a venture-backed Seed-stage SaaS company operating with the following inputs:

  • Cash in Bank: $500,000
  • Monthly Expenses: $60,000
  • Monthly Revenue: $20,000
  • Revenue Growth Rate: 5.0% Month-over-Month (MoM)

Step 1: Calculate Initial Net Burn = $60,000 - $20,000 = $40,000 per month

Step 2: Static Linear Runway = $500,000 ÷ $40,000 = 12.5 months

Step 3: Compounded Growth Extension = Factoring in a 5% monthly revenue expansion compounds revenue to $43,797 by month 16, extending total runway to 16.8 months

Step 4: Operational Break-Even Check = Monthly revenue reaches the $60,000 expenditure benchmark at Month 24. Because cash depletes at month 16.8, an interim financing round is required

Startup Runway Calculator preview showing burn rate, runway months, and cash balance by month
Figure 1: Fox Business Markets Startup Runway Calculator analyzing burn rate, cash out dates, and break-even milestones.

Industry Benchmarks for Startup Runway by Stage

Funding StageTarget Runway TargetDanger Zone (Red Alert)Fundraising Lead Time
Pre-Seed / Angel12 - 18 Months< 4 Months3 - 5 Months
Seed Stage18 - 24 Months< 6 Months4 - 6 Months
Series A21 - 30 Months< 7 Months6 - 9 Months
Series B & Beyond24 - 36 Months< 9 Months6 - 12 Months

Where to Find Your Numbers

Ensure reliable inputs by pulling data from your primary accounting ledgers and our companion financial tools:

  • Cash in the Bank: Check your real-time cash balances across business operating accounts in QuickBooks, Xero, or Brex.
  • Monthly Expenses (Gross Burn): Pull your trailing 3-month average total debits from your Income Statement (P&L). For team cost breakdowns, utilize our Cost per Employee Calculator.
  • Customer Acquisition Costs: Optimize marketing efficiency to reduce monthly cash drains using our CAC Calculator and Customer Lifetime Value (LTV) Calculator.
  • Growth Benchmarks: Track your multi-period compounding expansion with our CAGR Calculator.

What This Calculator Can and Cannot Tell You

✔ What This Tool Tells You:

  • Exact months of cash remaining under current burn trajectories
  • Calendar date when bank balances reach zero without intervention
  • Whether revenue growth can outpace expenses before cash runs out

✖ What It Does Not Cover:

  • Delayed accounts receivable collections (working capital lag)
  • Lumpy one-time annual software or tax expenditures
  • Dynamic hiring plan expense step-ups across future quarters

Related Calculators & Resources

Frequently Asked Questions

What is the difference between Gross Burn and Net Burn?

Gross Burn is the absolute total amount of cash leaving your bank account every month (total operational expenditures). Net Burn subtracts monthly incoming revenue from Gross Burn. Net Burn represents the true monthly cash deficit reducing your liquid reserves.

When should a startup begin pitching investors for its next round?

Founders should formally initiate investor discussions when they have 6 to 9 months of runway remaining. Closing institutional equity rounds routinely takes 3 to 6 months; waiting until you have fewer than 4 months of runway creates critical negotiation leverage loss.

How much runway should an early-stage startup target after raising?

In current venture market conditions, founders should raise enough capital to secure 18 to 24 months of runway. This provides 12 to 15 months to execute milestones and scale traction before entering the subsequent fundraising cycle.

Authoritative References & Methodologies

  • Y Combinator Startup Library: Managing Startup Cash Burn and Runway Planning
  • National Venture Capital Association (NVCA): Early-Stage Financial Benchmarks and Capital Planning