Burn Rate: Tracking How Fast You Spend Cash

Simple definition

Burn Rate is how much money your business spends each month beyond what it earns. There are two types: gross burn (total monthly expenses, ignoring revenue) and net burn (total expenses minus total revenue). Net burn is the number that matters because it tells you how fast your cash is actually disappearing.

If your gross burn is $5,000/month but you're earning $3,000 in MRR, your net burn is only $2,000. That's a very different survival equation. Solo founders often conflate the two and panic about their total spending when their net burn is actually manageable.

Why this matters

Burn Rate 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, burn rate 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

Net burn rate = Total monthly expenses - Total monthly revenue

Say your monthly costs break down as:

• Hosting & infrastructure: $180
• SaaS tools (analytics, email, etc.): $220
• Freelance designer: $800
• Your living expenses allocated to the business: $2,500
• Total: $3,700

Your MRR is $1,400.

Net burn = $3,700 - $1,400 = $2,300/month

Gross burn = $3,700/month

If you have $16,000 in the bank, net burn gives you 7 months of runway. Gross burn would make it look like 4.3 months. Use net burn for planning.

Example

You're building a form builder tool. Month 1: gross burn $3,200, MRR $0, net burn $3,200. Month 4: gross burn has crept to $3,800 (you added a Zapier integration that costs $100/month and bumped up your hosting), but MRR is now $1,600. Net burn is $2,200 -- actually lower than month 1 despite higher spending. The question isn't "am I spending too much?" but "is each dollar of new spending generating more than a dollar of new revenue?" If that $100 Zapier integration helped you close 5 new customers at $49/month, it paid for itself 2.4x in the first month.

Related reading

• Runway
• Gross Margin