Burn Rate: The Number That Killed My First Startup

How I Calculated My Burn Rate (Wrong) When we raised $320K, I built a financial model. It showed we'd spend $18,000/month in the early stages, growing to $25,000/month as we hired. Revenue would start at $0 and grow to $15,000/month by month six, $30,000 by month twelve. Breakeven at month fourteen. The spreadsheet was beautiful. Color-coded. Had charts. The investors loved it. Month one: Actual burn was $22,000. I'd forgotten to include employer payroll taxes, software subscriptions, and the legal fees for incorporation that hadn't hit yet. "One-time costs," I told myself. "It'll normalize." Month three: Actual burn was $31,000. We'd hired a junior developer ($7,500/month fully loaded) a month early because the product roadmap was behind schedule. Revenue was $0. I'd budgeted $3,000 in revenue for month three. We had zero paying customers. Month six: Burn was $34,000. Revenue was $1,800. The gap between my model and reality was widening every month. I told myself this was normal for SaaS startups. "You have to spend money to make money." I'm pretty sure every founder who runs out of cash tells themselves this at some point. The Two Burn Rates Nobody Tracks Gross burn: Total monthly cash out the door. My gross burn was $34,000 by month six. This is everything — salaries, rent, software, marketing, legal, meals, subscriptions, cloud hosting. All of it. Net burn: Monthly cash out minus monthly cash in. My net burn was $32,200 ($34,000 out, $1,800 in). This is the number that actually matters because it tells you how fast your cash is disappearing. I'd been tracking gross burn in my head but not calculating net burn correctly because the revenue number was too depressing to look at. I'd check Stripe, see $1,800, and immediately close the tab. Not a great financial management strategy. By month ten, our runway calculator (which I only started using after it was too late) showed: Cash remaining: $89,000 Monthly net burn: $28,400 (we'd cut some costs) Runway: 3.1 months Three months. Three. I had three months of cash left and a product that was generating $4,200/month in revenue against $32,600/month in costs. I should have started cutting immediately. Aggressively. Instead, I spent a month trying to raise more money. Fundraising took two months. We got six "we'll pass" emails and two "interesting but too early" responses. By the time I accepted that more money wasn't coming, we had $14,000 left. I laid off two of three employees, moved the remaining developer to part-time, and tried to pivot the product. It was too late. We lasted six more weeks. The Spreadsheet I Should Have Lived In Here's what I should have tracked weekly, not monthly: Cash on hand (actual bank balance, not projected) Monthly gross burn (all expenses, actual not budgeted) Monthly revenue (actual, not forecast) Net burn rate (gross burn minus revenue) Runway in weeks (cash ÷ (net burn ÷ 4.33)) I should have updated this every Monday morning and shared it with my co-founder. Instead, I updated a financial model quarterly and ignored the actual numbers in between. Our burn rate calculator does this automatically now. I wish it had existed in 2021.

Track your burn rate weekly. Not monthly. Not quarterly. Weekly. Set a recurring calendar reminder for Monday morning. Open your bank account. Note the balance. Note what came in and what went out. Calculate your net burn. Divide remaining cash by weekly net burn. That's your runway in weeks. If the number is below 16 weeks (four months), you need to act immediately. Distinguish between fixed burn and variable burn. Fixed burn is rent, salaries, insurance, software subscriptions. Variable burn is marketing, contractors, one-time purchases. If you need to cut costs fast, you can eliminate variable burn immediately. Fixed burn takes longer to reduce but has a bigger impact. Know both numbers. Set runway thresholds with pre-decided actions. If runway drops below 6 months: freeze hiring, cut marketing, reduce discretionary spending. Below 4 months: lay off non-essential staff, negotiate vendor contracts, pivot or shut down. Below 2 months: it's already too late for gradual action. Shut down gracefully or find emergency funding. The key is deciding what you'll do before you need to do it, when you're still thinking clearly. Never rely on projected revenue in your runway calculation. Count only revenue that's already hit your bank account. A signed contract that hasn't paid yet is not revenue. A pipeline of prospects is not revenue. A strong month-over-month trend is not revenue. Cash in the bank is revenue. Everything else is hope, and hope is not a financial strategy.

Using budget numbers instead of actuals. Your budget said you'd spend $18K/month. You actually spent $34K. The budget is a story you tell yourself. The bank statement is reality. Always use actuals for burn rate calculations. Our burn rate calculator only works if you feed it real numbers. Forgetting one-time costs that aren't one-time. Legal fees, equipment purchases, conference attendance, AWS overage charges — these "one-time" costs happen every few months. They're not one-time. They're periodic. Budget for them as recurring expenses with a quarterly frequency. Otherwise your burn rate is artificially low. Optimistic revenue forecasting. Every founder does this. Every single one. Including me, a CPA who should know better. If your revenue forecast shows hockey stick growth starting in month six, assume it starts in month twelve and comes in at 40% of what you projected. If the business still works with those pessimistic numbers, proceed. If it doesn't, the business model might not be viable yet. Some founders will read this and think it doesn't apply to them. That's what I thought too. I had a CPA license, a business degree, and two years of corporate finance experience. And I still managed to burn through $320K without ever honestly calculating how much time I had left. Don't be me. Track the number.