How to Calculate Burn Rate and Runway
Burn rate is how much cash your startup spends per month. Runway is how many months of cash you have left. These are the two most important numbers in your startup's financial life - and the first thing investors ask about.
The formulas are simple:
- Gross burn rate = Total monthly expenses
- Net burn rate = Total monthly expenses - Monthly revenue
- Runway = Cash in bank / Net burn rate
If you spend $30K/month and earn $5K/month, your net burn is $25K. With $300K in the bank, you have 12 months of runway.
Gross Burn vs. Net Burn
| Metric | Formula | What It Tells You |
|---|---|---|
| Gross burn | Total monthly spending | How much cash goes out the door regardless of revenue |
| Net burn | Spending - Revenue | How fast your cash is actually decreasing |
| Runway (gross) | Cash / Gross burn | Worst case - if revenue drops to zero |
| Runway (net) | Cash / Net burn | Realistic timeline assuming current revenue holds |
Investors care about net burn because it reflects your actual cash consumption. But track gross burn too - it tells you your exposure if revenue dips.
What Good Burn Rate Looks Like by Stage
| Stage | Typical Monthly Burn | What Drives It |
|---|---|---|
| Pre-seed (2-3 people) | $10K - $30K | Founder salaries, basic tools |
| Seed (5-10 people) | $30K - $80K | Engineering team, some marketing |
| Series A (15-30 people) | $80K - $250K | Full team, growth spend |
The biggest expense is always people. At pre-seed, most of your burn is founder living costs and basic infrastructure. At seed, 70-80% of burn is salaries.
This is the kind of financial analysis I do in business plan reviews - checking whether your burn assumptions are realistic and whether your raise amount actually gives you enough runway. Learn more about Business Plan Reviews.
When to Start Fundraising Based on Runway
The critical rule: start fundraising when you have 9-12 months of runway remaining.
| Remaining Runway | Status | Action |
|---|---|---|
| 18+ months | Comfortable | Focus on building, no urgency to raise |
| 12-18 months | Planning zone | Start preparing materials, building pipeline |
| 9-12 months | Active raise | Begin fundraising now |
| 6-9 months | Urgent | You're behind - raise immediately or cut burn |
| Under 6 months | Crisis | Drastic cuts needed, limited negotiating power |
Why 9-12 months? A well-prepared raise takes 6-10 weeks. But things go wrong - you might need to iterate on your pitch, expand your investor pipeline, or wait for a lead investor. Starting with 9-12 months gives you buffer.
Below 6 months, you're negotiating from desperation. Investors can tell. They'll offer worse terms or pass entirely. 82% of startup failures trace back to cash flow mismanagement.
How to Extend Your Runway Without Raising
Before raising another round, consider:
Cut burn:
- Reduce to essential headcount only
- Move to cheaper tools and infrastructure
- Defer founder salary increases
- Renegotiate vendor contracts
Increase revenue:
- Raise prices (most startups underprice)
- Focus on closing pipeline deals faster
- Offer annual prepayment discounts for cash upfront
- Add a service component to your product
Non-dilutive funding:
- Revenue-based financing (if you have $10K+ MRR)
- Government grants (EU Horizon, local innovation programs)
- Startup credits (AWS Activate, Google for Startups, NVIDIA Inception)
Want to stress-test your runway projections? I review business plans and financial models for early-stage founders - identifying unrealistic assumptions before investors do. Written feedback in 48 hours. Get a Business Plan Review - $600
The Burn Multiple: A Metric Investors Love
Burn multiple = Net burn / Net new ARR
This tells investors how efficiently you're converting cash into revenue growth.
| Burn Multiple | Rating | What It Means |
|---|---|---|
| Under 1x | Amazing | You're adding more ARR than you're burning |
| 1-2x | Great | Efficient growth |
| 2-4x | Average | Acceptable at early stages |
| Over 4x | Concerning | Burning too much relative to growth |
At pre-seed, burn multiple is less relevant because you may not have revenue yet. But by seed stage, investors increasingly care about this metric.
Common Burn Rate Mistakes
1. Not tracking burn monthly. Set up a simple spreadsheet or use a tool like Mercury or Brex that shows real-time burn. Check it every month without exception.
2. Ignoring one-time expenses. A $20K legal bill or $15K conference sponsorship can wipe out a month of runway planning. Budget for lumpy expenses.
3. Hiring too fast after raising. The temptation to hire immediately after closing a round is strong. But each hire adds $5-15K/month to burn permanently. Hire only when the role is critical to your next milestone.
4. Assuming revenue growth continues linearly. Revenue is lumpy, especially at early stages. Model your runway assuming revenue stays flat, not assuming continued growth.
Frequently Asked Questions
What is a good burn rate for a startup?
There's no universal "good" burn rate - it depends on your stage, revenue, and runway. The key metric is runway: you should always have 12+ months of cash at your current net burn rate. If your burn gives you less than 12 months, it's too high for your cash position.
How do investors evaluate burn rate?
Investors look at net burn relative to revenue growth (burn multiple). They want to see that you're spending efficiently - each dollar of burn is generating measurable progress. At pre-seed, they focus more on runway length. At seed and beyond, they focus on burn multiple.
When should a startup cut burn rate?
Cut burn when runway drops below 12 months and you're not actively raising. Don't wait until 6 months - by then, your options are limited. The easiest cuts are usually non-essential tools, unused subscriptions, and deferred hires.
How much runway should a startup raise for?
Target 18-24 months of runway in each raise. This gives you time to hit milestones and start your next fundraise from a position of strength. Raising for less than 18 months means you'll be fundraising again before you've proven anything.
Artem Luko is an angel investor based in Marbella, investing $25K-$3M in pre-seed and seed startups. Learn more at artemluko.com.