Calculator
Burn Rate & Runway Calculator
How long until the cash runs out? Enter your bank balance, monthly revenue, and expenses to see net burn, gross burn, and exactly how many months of runway you have left.
Cash & revenue
Total liquid cash available — bank balances, money-market funds, anything you can spend tomorrow.
Cash actually coming in each month. Use the conservative number, not contracted MRR.
Optional. Set to 0 for flat revenue (the safest assumption).
Monthly expenses
Calculations happen entirely in your browser. Nothing is saved or sent anywhere.
Net burn = expenses − revenue (the rate cash actually drains). Gross burn = expenses only (what you'd lose if revenue dried up). Default-alive means your growth gets you to break-even before the cash runs out.
How burn rate and runway work
Runway is the single most important number on a startup's dashboard: how long the company can keep operating before the cash runs out. It comes from two inputs — the cash in the bank, and the net monthly burn (expenses minus revenue). Once you know your net burn, runway is just division.
The formulas
- Gross burn = total monthly expenses
- Net burn = gross burn − monthly revenue
- Runway = cash in bank ÷ net burn (in months)
- Zero-cash date = today + runway months
Worked example
Scenario: £750,000 in the bank. Monthly expenses: £45k salaries + £8k rent + £6k software + £6k ads = £65,000. Monthly revenue: £15,000.
Gross burn: £65,000
Net burn: £65,000 − £15,000 = £50,000
Runway: £750,000 ÷ £50,000 = 15 months
Cut £10k of monthly spend (or grow revenue by £10k) and runway jumps to 18.75 months — every £1 saved is roughly a 1.5% extension of runway at this stage.
Frequently asked questions
What is burn rate?
Burn rate is the speed at which a startup is using up its cash. Gross burn is total monthly expenses; net burn is gross burn minus monthly revenue. Net burn is the figure that matters for runway because incoming revenue offsets the cash drain.
How is runway calculated?
Runway = Cash in bank ÷ Net monthly burn. £600,000 in the bank with £50,000 net burn gives 12 months of runway. If revenue grows or expenses fall, runway extends; if not, the clock runs out at the date the calculator shows.
What's a healthy amount of runway?
For early-stage startups, 18-24 months is the typical target after a funding round. Below 12 months you're in fundraising mode whether you want to be or not, because raising takes 3-6 months and you need a buffer in case it slips.
What's the difference between net and gross burn?
Gross burn is everything going out — salaries, rent, software, ad spend. Net burn subtracts revenue coming in. A company with £80k gross burn and £60k revenue has a net burn of £20k, which is the figure that determines runway.
How do I extend runway in a pinch?
In order of impact: cut variable spend (paid ads, contractors, non-essential SaaS), pause hiring, renegotiate vendor contracts, reduce founder/exec compensation, then last-resort layoffs. Increasing revenue is always preferable but rarely happens fast enough on its own.
When should I start raising the next round?
When you have 9-12 months of runway left, assuming you'd want to close the round before you hit 6 months. Investors discount valuations sharply when they sense a company is running on fumes, so raising from a position of strength is worth far more than raising as late as possible.