"How many sign-ups do you have right now?" - the founder will rattle off the number instantly. "How many months will the money in your account last?" - the founder will hesitate and start guessing. And it's precisely that guess that's the reason he'll wake up drenched in sweat at four in the morning.
In reality, there are only two numbers behind this nightmare:
- Burn rate: how much you're burning through each month.
- Runway: how many months you'll last on that account.
Calculating them takes five minutes, but they're ignored more often than people are willing to admit. Below, we'll cover how to calculate burn rate correctly, how to extend a project's lifespan without slowing down growth, and what red flags to watch out for, before the money runs out completely.
What Burn Rate and Runway Mean
Your burn rate is the cash your company loses in a month. It comes in two versions, and the gap between them matters. Gross burn is everything going out: salaries, rent, software, contractors, ads, the lot. Net burn is that number minus whatever came in. If you spend 40,000 and collect 10,000 in revenue, gross burn is 40,000 and net burn is 30,000. When people say cash burn without specifying, they usually mean net.
The runway is simpler. Take the cash in your bank account and divide it by net monthly burn. That's how many months you can keep operating before the account hits zero, assuming nothing changes.
For a pre-seed startup, these two figures matter more than almost anything else on a dashboard. Revenue can be flat for a while, and the company survives. Cash reaching zero ends the story on a specific date, and no amount of good intentions moves that date. That's why cash burn deserves a fixed slot in your month rather than an occasional check.
Here's a figure to hold onto for the next section: 240,000 in the bank, 30,000 net burn a month, eight months of runway. Everything else is a variation on that arithmetic.
How to Calculate Your Burn Rate and Runway
How to calculate burn rate takes about ten minutes with a bank statement open. The steps:
- Pick the most recent complete month.
- Add up every payment that left the account. That's gross burn.
- Add up the cash that actually landed, not invoices you sent. That's your inflow.
- Subtract inflow from gross burn. That's net burn, your real monthly number.
- Repeat for three months and average them, because one month is never typical.
The runway calculation is the easy half. Cash in the bank divided by net monthly burn.
Take a team with 240,000 left after a pre-seed round. They spend 52,000 a month and collect 22,000 in revenue, so net burn is 30,000. Divide 240,000 by 30,000, and you get eight months. Not a comfortable number, but it's clear.
Gross and net both earn their keep, in different conversations. Gross burn shows what your cost base looks like if revenue disappeared tomorrow, which is exactly what a big customer churning creates. Net burn shows what's happening now and is the number investors ask for. Track both; quote net.
One more step people skip. Project the number forward instead of freezing it. If revenue grows 15 percent a month and costs stay flat, net burn shrinks, and your real runway is longer than the division suggests. If you're about to hire two engineers, burn jumps before anyone writes a line of code. Build a month-by-month sheet with cash at the start, expected inflow, expected outflow, and cash at the end. Doing how to calculate burn rate properly means keeping that sheet updated, not taking one snapshot.
How to Extend Your Runway
Cutting costs is the obvious lever, but not every cut is equal. These reliably lower monthly burn rate without breaking anything:
- Hiring pace. Delaying one senior hire by three months is often a full extra month of runway.
- Tooling. Most early teams pay for software nobody has opened in six weeks. Audit the subscriptions quarterly.
- Contractors over full-time roles for work that isn't permanent yet.
- Paid acquisition that hasn't proven a payback period. Pause it rather than shrink it.
- Cloud spend, which grows quietly and rarely gets reviewed.
Some ways to extend the cash runway don't involve cutting at all. Move customers to annual prepaid plans, since a year upfront is cash today. Negotiate payment terms with suppliers, and chase overdue invoices properly, because unpaid receivables are your money sitting in someone else's account.
Founders get the trade-off wrong in both directions. Cut too deep, and you protect the cash while killing the growth that justified raising it, so you arrive at the next round with more months and no story. Spend freely, and you buy growth you can't sustain. A useful test for any expense is whether it moves a metric an investor will ask about.
As a rule of thumb, keep at least six months of cash runway in reserve before you start raising again. Raising takes three to six months in a decent market, and negotiating while you can still walk away is a completely different conversation than negotiating while the payroll clock ticks.
Warning Signs and When to Raise
Some signals in your startup finance show up months before the crisis does:
- Runway shrinking faster than the calendar, which means burn is rising quietly.
- Flat revenue with growing headcount.
- Not knowing your net burn without opening a spreadsheet.
- Regularly pushing planned spend into next month to make this month look fine.
The standard guidance is to hold 12 to 18 months of startup runway after a raise. Twelve is tight, eighteen is comfortable, and under nine means fundraising becomes your full-time job whether you want it to be or not.
Burn and startup runway set the timing of the next raise, not your mood or the market. Work backward: pick the point where you'd want six months of cash left, then subtract the months a raise will take. That date is when the process starts, and it's usually earlier than founders expect.
Raising too late is the expensive mistake. With two months of cash left, every investor can see it in your numbers and terms move accordingly. Whether you track this in a spreadsheet, with an accountant, or in a tool like solvee matters far less than checking it before the number becomes urgent.
Why Burn Discipline Signals a Strong Founder
Investors read your burn rate as a character reference. A founder who knows the numbers cold, explains what each cost buys, and can say what they'd cut first if a round fell through is someone you can trust with more money. The opposite reads as risk, no matter how good the traction looks.
There's a practical reason too. Every month you extend is another attempt to get the product right, and few teams find product-market fit on the first try. Low burn buys more attempts, and that's the real advantage, not frugality for its own sake.
Discipline is not the same as starving the company. Teams that underspend on the one thing clearly working lose as reliably as teams that overspend on everything. The goal is deliberate spending, where each high cost has a job, and you know what happens if you stop it.
Survival comes from knowing your numbers. Growth comes from what you do with the months they buy you.
Frequently Asked Questions
What is burn rate? Burn rate is how fast your company spends cash, measured monthly. Gross burn is everything leaving the account. Net burn is that total minus incoming revenue. Most founders quote net burn, because it reflects the real speed at which the bank balance is falling.
How do you calculate runway? Divide the cash in your bank account by your net monthly burn. If you hold 240,000 and lose 30,000 a month after revenue, you have eight months of runway. Use a three-month average of burn rather than a single month, which is rarely typical.
What is the difference between gross and net burn? Gross burn is total monthly spend, ignoring income. Net burn subtracts revenue from that spend. Gross shows your cost base if revenue vanished, which matters when one customer is large. Net shows what's actually happening now and is the figure investors ask for.
How much runway should a startup have? Aim for 12 to 18 months after a raise, and start fundraising while at least six months remain. Raising typically takes three to six months, so negotiating with a comfortable buffer keeps leverage on your side, not the investor's.
Control Your Numbers, With solvee
Founders rarely avoid their finances because the math is hard. They avoid it because opening the sheet makes the situation real. That's the gap solvee is built for. It's a personalized AI accelerator that works through your business with you, including your financial model, so burn and runway stop being a background worry and become numbers you check on purpose.
The fit is practical. solvee helps you lay out your costs, project cash forward month by month, and see what your burn rate does when you make a hire or turn on ads. Instead of one static figure, the product gives you a view of how long the money lasts and which levers change that answer.
The real problem is timing. Most founders look properly at the numbers when they have four months of cash left, after the good options have already expired. Guided strategy work turns it into a routine step instead of an emergency.
Want to know exactly how long your money lasts before it becomes urgent? Get free access to solvee. No credit card, no equity, start today.