Cash runway calculator: when will your cash run out?

Worked example: 52,000 out, 28,000 in, 180,000 in the bank

Runway is cash in the bank divided by net monthly burn. The calculator opens with a seed-stage company that has €180,000 in the bank, €52,000 going out and €28,000 coming in: net burn is €24,000 and runway is 7.5 months. A 10 percent spending cut adds 2.1 months, and 25 percent more revenue adds 3.1, so the levers are not symmetric.

The Corporate Finance Institute defines runway the same way, as cash on hand divided by monthly net burn, in its cash runway guide.

net burn = 52,000 - 28,000
         = 24,000 a month
runway   = 180,000 / 24,000
         = 7.5 months

cut spend 10%:
  net burn = 46,800 - 28,000 = 18,800
  runway   = 9.6 months (+2.1)
grow revenue 25%:
  net burn = 52,000 - 35,000 = 17,000
  runway   = 10.6 months (+3.1)

Two things stand out. First, 7.5 months means cash runs out in about seven and a half months if nothing changes; the calculator turns that into a calendar month so it stops being abstract. Second, the levers are not symmetric. A 10 percent cut adds 2.1 months, not 10 percent of 7.5, because you are shrinking the number you divide by. Here, growing revenue by a quarter buys more time than the cut, but a cut takes effect this month and revenue growth is a forecast. Most founders who are short on time do the cut first.

How to read your result

Your result falls into one of three bands: under 6 months, 6 to 12 months, or 12 months or more. Under 6, a raise usually takes longer than the time you have left, so cut costs first. From 6 to 12 there is room to raise if you start now. At 12 or more you can invest in growth. The bands follow the fundraising timelines quoted below and are a default, not a law.

• Under 6 months. A raise usually takes longer than you have left. Cut costs first, then fundraise from what you saved. Look at the biggest line in money out, which is almost always payroll.
• 6 to 12 months. Enough to raise, if you start now. Build the investor list this month rather than at month three, and decide in advance which costs you would cut if the round slips.
• 12 months or more. You have room to invest in growth. The useful question becomes what each hire or spend does to this number, before you commit to it.

How many months of runway should you have?

The common answer is 18 to 24 months after a raise. Pilot's runway guide says that is what investors commonly expect, that most startups begin raising with about 12 months left, and that a raise takes roughly four to nine months. NYU's entrepreneurship team makes the same case in The Runway Equation: if a round takes about six months to close, raising only 12 months of cash leaves six months to show progress before you are fundraising again.

So the number to watch is not only runway, but runway minus the time a raise takes. With the worked example above, 7.5 months minus a six-month raise leaves a month and a half of slack. That is why the example company should cut before it raises. If you are deciding how much to raise, read how much runway to raise.

Getting the three inputs right

Use three numbers for a normal month: cash you can spend today, money out and money in. The common mistake is letting one-offs in. Leave out a round that has not closed, a one-time legal bill and a big project payment, because none of them repeat, and add the full monthly cost of a hire who starts next month.

• Cash in the bank: money you can spend today. Leave out a round that has not closed and invoices that have not been paid.
• Money out: a normal month. Leave out one-off costs like a legal bill or a laptop order; they reduce cash once but do not repeat. If a hire starts next month, add their full monthly cost now, because that is the burn you will actually run at.
• Money in: revenue that repeats. A single big project payment makes one month look better than the next ones will be.

To see gross and net burn as separate numbers first, use the burn rate calculator. For the thinking behind the date itself, read when will I run out of cash.

How Plainhub keeps runway live

This page answers the question once. In Plainhub, runway is recalculated every time you record something: a new hire on the People page, a recurring cost or a customer payment. It uses the same formula as this calculator, cash divided by net burn, and it follows the advice above on one-off costs: they reduce your cash, but they never count as burn.

• The cash-out month, before you commit. On the Plans page you add a plan such as a hire or more ad spend as a draft and see runway before and after, the new net burn and the cash-out month side by side, up to three plans at once.
• A warning when it gets short. A runway alert appears once you are under six months, and it turns critical under three.
• No bank login. You type in what happened. Plainhub never asks for bank access, statement uploads or accounting integrations.

You can click through a sample workspace in the Try the live demo without signing up.