What is Startup Burn Rate?
Burn rate is the speed at which a startup spends its cash reserves before generating positive cash flow. Gross burn rate is total monthly expenses regardless of revenue, while net burn rate subtracts revenue from expenses. Combined with your cash balance, it determines your runway, the number of months before you run out of money.
The Formula
Formula
Gross Burn Rate = Total Monthly Expenses Net Burn Rate = Monthly Expenses − Monthly Revenue Runway = Cash in Bank ÷ Net Burn Rate
Always use net burn for runway calculations, as it reflects your actual cash consumption rate.
Worked Example
Worked example
A seed-stage startup has $500,000 in the bank, $50,000/month in expenses, and $15,000/month in early revenue.
- 01Gross Burn Rate = $50,000/month
- 02Net Burn Rate = $50,000 − $15,000 = $35,000/month
- 03Runway = $500,000 ÷ $35,000 = 14.3 months
- 04Cash-out date ≈ 14 months from now
Result
The startup has ~14 months of runway. They should begin fundraising conversations at month 8 (6 months before cash-out), as raising typically takes 3-6 months.
Why This Matters
Fundraising timing
Start raising when you have 6-9 months of runway remaining. CB Insights research shows that startups that begin fundraising with 9+ months of runway close their rounds in a median of 89 days, while those starting with fewer than 4 months close in 118 days at terms 20-30% worse, confirming that fundraising timing relative to burn is the single highest-leverage negotiation lever founders control. Wait too long and you'll negotiate from a position of desperation, leading to worse terms. Use our Runway Extension Calculator to model different scenarios.
Hiring decisions
Every new hire increases burn by $8,000-$15,000/month (fully loaded) according to Kruze Consulting startup benchmarks. Use the Employee Cost Calculator to understand the true cost before committing.
Pivot capacity
Your runway determines how many pivots you can afford. Y Combinator data shows that startups with 18+ months of runway at their first major pivot have a 3x higher probability of finding product-market fit than those pivoting with under 6 months remaining, because adequate runway allows genuine market testing rather than the desperate shortcutting that runway pressure induces. Track your revenue growth rate alongside burn to know if you're trending toward sustainability.
Common Mistakes
Using gross burn instead of net
Gross burn ignores revenue entirely. If a startup brings in $20K/month on $50K in expenses, the actual burn is $30K, not $50K. Using gross burn creates unnecessary panic. Kruze Consulting data shows that 35% of pre-seed founders incorrectly use gross burn to calculate runway, overstating their cash urgency and triggering premature fundraising that costs them additional equity dilution compared to founders negotiating with accurate net burn calculations.
Forgetting one-time costs
Annual payments (insurance, software licenses), quarterly tax obligations, and one-time costs (office setup, equipment) are not captured in monthly burn but significantly impact cash. Y Combinator research on startup cash management found that founders using monthly burn as their sole metric ran into cash surprises an average of 2.3 times per year due to non-monthly obligations, with the average surprise consuming 1.4 months of projected runway.
Assuming linear burn
Burn rate is not constant. Hiring, marketing campaigns, and seasonal effects create spikes. Use a 3-month rolling average for more accurate runway estimates. Andreessen Horowitz finance team research recommends 13-week cash flow forecasting; their data shows that companies using 90-day rolling burn averages are within 10% of actual cash-out dates 85% of the time, versus 58% accuracy for companies using a single trailing month.
Industry Benchmarks
Source: Kruze Consulting Startup Benchmarks