What is startup runway?

Runway is the number of months your business can keep operating before it runs out of cash, assuming nothing changes. The simple version is cash in bank divided by net monthly burn. The useful version accounts for revenue growth and planned hires, because both change the burn rate as the months pass.

How do you calculate net burn?

Net burn is total monthly costs minus monthly revenue. Total costs means payroll including tax and benefits, plus rent, software, contractors and every other operating cost. If revenue exceeds costs, net burn is negative - that is break-even or better.

How much runway should a startup have?

Eighteen months is the number most investors want to see after a round closes - twelve months to hit the milestones for the next raise, six months to actually run the process. Below twelve months you are negotiating from a weak position. Below six months, terms get decided by whoever has the cash.

When should I start fundraising?

Allow six months from first conversation to money in the bank, and start before your runway drops under nine months. A raise that has to close takes worse terms than a raise that can walk away, and investors can tell the difference from the first meeting.

Does this calculator store my numbers?

No. Everything runs in your browser - nothing is sent to a server, there is no sign-up and no data is stored. The share link encodes your inputs in the URL itself, so it only exists if you choose to copy it.

Startup Runway Calculator - Free, No Sign-Up

Startup finance

What runway actually tells you

Runway is the number of months you can keep going before the cash runs out. The arithmetic is trivial - cash divided by net burn - and that simplicity is exactly why most founders get it wrong. A static division assumes your revenue and your costs stay frozen, and they never do.

This calculator runs the month-by-month version instead. Revenue compounds at your growth rate, costs step up when hires land, and cash is drawn down against the gap between the two. That's why the number here is usually different to the one in your spreadsheet - and usually more honest.

The formula, and where it breaks

Net burn is total monthly costs minus monthly revenue. Runway is cash divided by net burn. The formula breaks in three predictable places: growth (revenue at month 18 is nothing like revenue today), hiring (each hire is a permanent step change in burn, not a one-off cost), and timing (a raise that lands in month 8 does nothing for a cash crunch in month 6).

Why the fundraising date matters more than the runway number

A round takes about six months from first conversation to money in the bank. If you start at nine months of runway, you have a buffer and you can walk away from bad terms. If you start at six, you are negotiating with a deadline that the other side can see. If you start at three, the terms are whatever they say they are.

That's the number this tool leads with, and it's the one worth putting in your calendar.

months investors want to see post-raise

months to run a round, start to close

months of runway: start the conversations

of your numbers leave this page

The four inputs

What to put in each box

Cash in bank

Every liquid dollar you can actually spend. Include the term deposit that matures this quarter. Exclude invoices you're still chasing and any grant that hasn't been signed.

Monthly costs

Everything that leaves the account in a month. Payroll including tax, KiwiSaver and benefits - not headline salaries. Rent, software, contractors, cloud, accounting, insurance.

Monthly revenue

Recurring revenue you can bank on. Contracted MRR, not pipeline. Set it to zero if you're pre-revenue - the tool handles that case properly rather than dividing by nothing.

Revenue growth

Your realistic month-on-month growth, net of churn. Use the last three months' actual average, not the board-deck number. Negative is allowed, and worth modelling honestly.

The two toggles handle the scenarios that actually change the answer: planned hires, which permanently raise burn from the month they land, and a raise, which drops a lump of cash in at a month of your choosing. Everything recalculates as you move a slider.

Common questions

Runway questions, answered

Runway is the number of months your business can keep operating before it runs out of cash, assuming nothing changes. The simple version is cash in bank divided by net monthly burn. The useful version - the one this calculator runs - accounts for revenue growth and planned hires, because both change the burn rate as the months pass.
Net burn is total monthly costs minus monthly revenue. Total costs means fully loaded payroll - salaries plus tax, KiwiSaver and benefits - plus rent, software, contractors and every other operating cost. If revenue exceeds costs, net burn is negative, which is break-even or better and means your runway is effectively unlimited at current trajectory.
Eighteen months is the number most investors want to see after a round closes: twelve months to hit the milestones for the next raise, six months to run the process. Below twelve months you're negotiating from a weak position. Below six, the terms get decided by whoever has the cash. The gauge in the tool is scaled against exactly these thresholds.
Allow six months from first conversation to money in the bank, and start before runway drops under nine months. A raise that has to close takes worse terms than a raise that can walk away, and experienced investors can read the difference from the first meeting. The calculator gives you the specific month.
Set monthly revenue to zero and ignore the growth slider. Runway becomes cash divided by monthly costs, break-even reports as not reached within the modelled period, and the fundraising date is the number that matters. That is the correct reading of your situation, not a limitation of the tool.
No. Everything runs in your browser. There is no sign-up, no server call and no analytics on the inputs themselves. The share link encodes the numbers in the URL, so it only exists if you choose to copy it - and anyone you send it to can see those figures, which is worth remembering before you paste it into a group chat.
Whichever one you're thinking in. The maths is currency-agnostic - put NZD in and you get NZD out. Just don't mix currencies between the fields.

This is what an interactive tool does for you

A calculator like this gets bookmarked, shared and linked to for years - and gives your sales team a reason to reach out that isn't a cold pitch. I build them for B2B companies in one to three weeks.

Talk about building one →