Burn Rate Calculator Formula

Understand the math behind the burn rate calculator. Each variable explained with a worked example.

Formulas Used

Gross Burn Rate (monthly)

gross_burn = monthly_expenses

Net Burn Rate (monthly)

net_burn = monthly_expenses - monthly_revenue

Cash Runway

runway_months = (monthly_expenses - monthly_revenue) > 0 ? cash_balance / (monthly_expenses - monthly_revenue) : 0

Variables

VariableDescriptionDefault
cash_balanceCurrent Cash Balance(USD)500000
monthly_expensesMonthly Expenses(USD)80000
monthly_revenueMonthly Revenue(USD)30000

How It Works

How to Calculate Burn Rate and Runway

Formula

Gross Burn = Monthly Expenses Net Burn = Monthly Expenses - Monthly Revenue Runway = Cash Balance / Net Burn

Burn rate is how fast a startup spends its cash reserves. Gross burn counts all spending. Net burn subtracts revenue, giving the actual cash outflow. Runway is the number of months until the cash runs out at the current net burn rate. Startups typically aim to maintain at least 12-18 months of runway to give themselves time to reach profitability or raise the next round.

Worked Example

A startup has $500,000 in the bank, spends $80,000/month, and earns $30,000/month in revenue.

cash_balance = 500000monthly_expenses = 80000monthly_revenue = 30000
  1. 01Gross Burn = $80,000/month
  2. 02Net Burn = $80,000 - $30,000 = $50,000/month
  3. 03Runway = $500,000 / $50,000 = 10.0 months

Ready to run the numbers?

Open Burn Rate Calculator