one-line definition
Monthly burn is the total amount of cash your business spends each month, regardless of revenue — it tells you how fast you are depleting your reserves.
formula: Gross Burn = Total monthly expenses. Net Burn = Total monthly expenses − Total monthly revenue. Runway = Cash in bank ÷ Net burn.
tl;dr
Low burn buys time. Time lets you iterate. Iteration leads to product-market fit. Every dollar you add to your monthly burn shortens your runway and raises the stakes. The solo founders who survive are the ones who keep burn embarrassingly low until revenue proves the model.
Simple definition
Monthly burn is your business's cash outflow per month. It is a straightforward number: add up everything you pay for — hosting, SaaS tools, contractors, ads, your own salary if you take one. That total is your gross burn. Subtract any revenue, and you get net burn — the amount your bank account shrinks each month. For solo founders, net burn is the number that matters because it directly determines how many months you can keep going before the money runs out.
Why this matters
Monthly Burn is a critical metric for bootstrapped founders because it represents the truth about your business. Before product-market fit, this metric may feel abstract. But once you have paying customers and recurring revenue, ignoring this metric becomes dangerous to your growth trajectory.
Most solo founders make the mistake of focusing on the wrong metric at the wrong time. Before $1k MRR, the best metrics are activation and product-market fit. Between $1k-$10k MRR, monthly burn becomes highly relevant. Beyond $10k MRR, it becomes one of your top three growth levers.
The reason solo founders rarely fail due to lack of brilliant ideas. They fail because they don't systematically measure metrics that matter and don't iterate on improvements.
Common mistakes
1. Calculating too early. If you have 5 customers, this metric is noise, not signal. Wait until you have at least 50 customers and 2-3 months of data before drawing conclusions. Too early and you'll see random variance, not real patterns.
2. Ignoring variations by segment. Your customers acquired via blog may behave differently than those acquired via paid ads. Your enterprise customers may function differently than your small-biz customers. Always segment your metrics to see the true signal.
3. Optimizing without context. Improving this metric by 10% means 10% more revenue? Not necessarily. Understand upstream and downstream impact before optimizing. Focus on the change that will have the biggest impact on revenue.
4. Forgetting causality flows both directions. A low metric may indicate a product issue, a positioning issue, or that you're attracting the wrong customers. Before optimizing, understand why it's low.
How to act on this
Calculate this metric for your last 30 customers right now. Do you have the data? If yes, establish a baseline and write it down. That's your first step toward improvement.
Identify your highest-value customer segment. Is it a specific monthly cohort? An acquisition channel? A customer type? Focus on that segment and try to improve this metric for them.
Run one small experiment to improve this metric by 5-10%. Measure, learn, iterate. The compounding of these small improvements over 12 months creates a huge difference.
How to calculate it
Gross Burn = Sum of all monthly expenses Net Burn = Gross Burn − Monthly Revenue Runway = Cash reserves ÷ Net Burn
Break down your burn into categories:
| Category | Monthly cost |
|---|---|
| Hosting (Vercel, Supabase) | $45 |
| SaaS tools (email, analytics) | $60 |
| Domain + DNS | $3 |
| Ads (Google, Twitter) | $300 |
| Contractor (design, 5 hrs) | $250 |
| Gross Burn | $658 |
| Revenue | −$420 |
| Net Burn | $238 |
With $5,000 in savings, you have 21 months of runway at this net burn. Cut the ads and contractor, and net burn drops to $108/month — extending runway to 46 months. That flexibility matters.
Example
You quit your job with $15,000 saved and start building a SaaS product. Month 1-3: pure building, zero revenue. Gross burn: $400/month (hosting, tools, coffee shops). $13,800 left. Month 4: you launch, get 8 paying users at $19/month = $152 revenue. Net burn drops to $248. Month 6: 22 paying users, $418 revenue. Net burn: -$18. You just crossed into profitability — and you still have $12,300 in savings as a buffer. If you had spent $2,000/month on a designer, office space, and premium tools, you would have burned through $12,000 by month 6, with only $3,000 left and the pressure of running out of money clouding every product decision.
Related reading
Related terms
- Burn Rate
- Runway
- Ramen Profitability
FAQ
What is the difference between gross burn and net burn?+
Gross burn is everything you spend: $4,000/month in total costs. Net burn subtracts revenue: if you earn $1,500 and spend $4,000, your net burn is $2,500/month. Net burn is what determines your runway. Investors ask about net burn. Your bank account cares about net burn.
What is a healthy monthly burn for a bootstrapped solo founder?+
As low as humanly possible until you have consistent revenue. Many successful bootstrapped products were built on under $200/month in costs (hosting, domain, email service). If your monthly burn is $500 and your savings are $10,000, you have 20 months to reach profitability. Keep burn low and you buy yourself time — the most valuable resource for a new product.