Net Burn vs Gross Burn

Understanding the Formulas

Gross Burn Rate: Total monthly operating expenses. This includes everything: salaries, benefits, rent/office, software subscriptions, cloud hosting, professional services, marketing spend, and any other recurring costs. Gross burn tells you the total cash outflow from operations if you had zero revenue. It represents your cost structure and spending velocity.

Net Burn Rate: Gross Burn minus Revenue. Formula: Net Burn = Total Expenses - Total Revenue. This is the actual cash you lose each month. If you spend $100k and earn $40k, you net burn $60k. If you spend $100k and earn $100k, you are break-even (net burn = $0). If you spend $100k and earn $120k, you have negative net burn of -$20k, meaning you are generating cash.

Why the Distinction Matters: Investors and board members care about both numbers for different reasons. Gross burn shows your cost discipline and spending capacity. Net burn shows your actual cash runway. A company with $200k gross burn and $150k revenue is in better shape than a company with $100k gross burn and $20k revenue, even though the first has higher absolute expenses. Context matters.

Example Calculations

Example 1: Pre-Revenue Startup - Monthly expenses: $80k (team, hosting, tools). Monthly revenue: $0. Gross Burn: $80k. Net Burn: $80k - $0 = $80k. For pre-revenue companies, gross and net burn are identical. Every dollar spent is a dollar of runway consumed.

Example 2: Early Revenue Stage - Monthly expenses: $120k. Monthly revenue: $30k. Gross Burn: $120k. Net Burn: $120k - $30k = $90k. The company is spending $120k to operate but only consuming $90k of cash because revenue offsets $30k. Runway should be calculated using the $90k net burn figure.

Example 3: Scaling Company - Monthly expenses: $500k. Monthly revenue: $450k. Gross Burn: $500k. Net Burn: $500k - $450k = $50k. Despite high absolute spending, this company only burns $50k/month in cash. With $1M in the bank, they have 20 months of runway—not 2 months if you mistakenly used gross burn.

Example 4: Cash Flow Positive - Monthly expenses: $200k. Monthly revenue: $250k. Gross Burn: $200k. Net Burn: $200k - $250k = -$50k. Negative net burn means the company generates $50k cash per month. Runway is essentially infinite from operations alone—the business is self-sustaining and growing its cash position.

Common Mistakes and Misunderstandings

Mistake 1: Using Gross Burn for Runway - If you calculate runway as Cash / Gross Burn, you will dramatically underestimate your actual runway. A company with $600k cash, $100k gross burn, and $40k revenue appears to have 6 months runway (gross) when they actually have 10 months (net). This mistake causes unnecessary panic and poor decisions.

Mistake 2: Ignoring Revenue Volatility - Net burn assumes stable revenue. If your revenue is volatile or declining, using current net burn overstates future runway. When revenue might drop, model scenarios: current revenue, 20% drop, 40% drop. Understand how runway changes under stress. Net burn is only accurate if revenue holds.

Mistake 3: GAAP vs Cash Basis - Net burn should be calculated on a cash basis, not accrual. Cash burn is actual dollars leaving your bank. Accrual accounting includes expenses incurred but not yet paid and revenue earned but not yet collected. For runway purposes, cash is king. Use your bank statement, not your income statement.

Mistake 4: One-Time vs Recurring - Both gross and net burn should reflect normalized monthly spend. If you paid a $50k annual contract in January, do not report $150k gross burn that month. Normalize to $100k + ($50k/12) = $104k. Investors and board members want to see run-rate burn, not lumpy cash movements.

Which Metric to Use When

Use Gross Burn for: Understanding your cost structure. Benchmarking against peer companies (gross burn per employee is a common metric). Planning budget allocations. Identifying largest expense categories for optimization. Communicating spending discipline to investors. Modeling what happens if revenue goes to zero.

Use Net Burn for: Calculating runway (always). Determining fundraising timing. Tracking cash efficiency month-over-month. Modeling path to profitability. Setting cash management triggers. Communicating financial health to stakeholders. Net burn is the operational reality; gross burn is the structural baseline.

Report Both: In board updates and investor communications, report both numbers. Showing Gross Burn: $120k, Revenue: $40k, Net Burn: $80k gives a complete picture. Investors can see your cost structure, revenue progress, and cash consumption in one view. Hiding either number creates suspicion. Transparency builds trust.

Actionable Steps

1. Calculate Both Numbers Monthly: At month-end, sum all cash expenses (gross burn) and subtract all cash receipts (revenue). Track both in a spreadsheet or dashboard. Trend analysis over 6-12 months reveals patterns you might miss in a single snapshot.

2. Normalize for Timing: Spread annual payments across 12 months. Remove one-time expenses from recurring burn calculations. Create both a GAAP view (for accounting) and a cash/normalized view (for operational decisions). Label clearly which you are using.

3. Build a Burn Waterfall: Break gross burn into categories: People (salaries, contractors), Infrastructure (hosting, tools), Office (rent, utilities), Marketing (ads, events), Professional Services (legal, accounting), Other. Know which buckets are fixed vs variable, essential vs discretionary. This enables surgical cuts if needed.

4. Set Burn Rate Targets: Determine your target net burn based on runway goals. If you want 18 months runway and have $900k cash, target net burn is $50k or less. Work backward from runway goal to burn target to expense budget. Do not set expenses first and hope runway works out.

5. Scenario Model Revenue Risk: Calculate runway at current revenue, 80% revenue, 60% revenue, and zero revenue. Understand how quickly runway collapses if revenue underperforms. If revenue drop by 30% cuts runway from 15 months to 8 months, you have revenue concentration risk that needs addressing.

Frequently Asked Questions

Disclaimer: This content is for educational purposes only. Consult with financial advisors for company-specific decisions.