For any startup or early-stage company, burn rate is the single most important number on the dashboard. It tells you how fast cash is leaving the business, and — combined with your cash balance — it gives you your runway: the number of months you have before the lights go off. This calculator computes both in seconds, entirely in your browser.
What is burn rate?
Burn rate comes in two flavours:
- Gross burn is every pound, dollar or euro that leaves your bank in a month — payroll, AWS bill, rent, software subscriptions, the lot. It answers the question: “If revenue disappeared overnight, how long would we last?”
- Net burn is gross burn minus monthly revenue. It is the amount your cash balance actually shrinks each month under normal trading. A company spending £80,000 and earning £20,000 has a net burn of £60,000.
Both numbers matter. Investors asking “what is your burn rate?” almost always mean net burn. Your team asking “are we going to make payroll?” are living in gross-burn territory.
How the calculator works
The maths is deliberately simple — the value is in making the numbers visible and acting on them.
Net Burn = Monthly Expenses − Monthly Revenue
Runway (months) = Cash Balance ÷ Net Burn
If net burn is zero or negative (revenue exceeds expenses), the company is self-sustaining and the runway from a cash perspective is effectively unlimited. The calculator also shows gross runway — what happens if you had no revenue at all — as a stress-test figure.
The estimated run-out date is today’s date plus runway months, giving a concrete calendar deadline rather than an abstract number.
The funding needed for 18-month safety field calculates how much new capital would be required to bring runway up to the 18-month benchmark, assuming burn and revenue stay constant.
Worked example
A UK SaaS startup has:
| Input | Value |
|---|---|
| Cash balance | £500,000 |
| Monthly expenses (gross burn) | £80,000 |
| Monthly revenue (MRR) | £20,000 |
Calculation:
- Net burn = £80,000 − £20,000 = £60,000/month
- Runway = £500,000 ÷ £60,000 = 8.3 months (approximately August 2026 from June 2026)
- Revenue coverage = 20,000 ÷ 80,000 = 25% of expenses covered
- Funding needed for 18-month runway: 18 × £60,000 − £500,000 = £580,000 in new capital
That 8.3-month runway falls in the “Danger zone” band — enough time to close a seed round only if fundraising starts immediately.
Burn rate benchmarks
| Monthly net burn | Context |
|---|---|
| Under £10,000 | Solo founder or tiny team; typical pre-product |
| £10,000–£50,000 | Seed stage, 3–8 person team |
| £50,000–£200,000 | Post-seed, scaling to Series A |
| £200,000–£1,000,000 | Series A, rapid hiring and growth |
| Above £1,000,000 | Series B+ hyper-growth or deep-tech |
These are rough guides — what matters is the ratio of burn to progress (revenue growth, user growth, key hires). A £200,000/month net burn funding 40% month-on-month MRR growth may be entirely rational; the same burn going on ping-pong tables is not.
Formula note
All calculations follow standard startup finance conventions:
- Net burn = total cash outflows − cash inflows in a given period (monthly here)
- Runway = cash ÷ net burn — no compounding, no interest, linear projection
- Gross runway = cash ÷ gross burn (worst-case, zero revenue scenario)
- The 18-month funding target is widely used in venture circles as the minimum safety buffer for running a non-distressed fundraising process
Everything runs client-side in your browser. No data is sent to any server.