Skip to content
calcbloc
RUNWAY / STARTUP

Startup runway calculator

Work out how many months your cash lasts at your current burn, with optional monthly growth in revenue and costs, and whether you reach break-even first.

Written by Reviewed by TODO Reviewer NameLast verified Updated

Your details

01Today

02Growth

Runway

12.0 months

cash runs out before revenue covers costs: default dead

Runway at today's burn
12.0 months
Net burn per month
$100,000
Revenue covers costs from
Not before cash runs out
Default alive
No
  • Runway = cash ÷ monthly net burn, where net burn = expenses − revenue. With growth rates entered, the calculator steps through each month instead, so a growing revenue line lengthens runway and rising costs shorten it.
  • No growth entered: runway is simply cash divided by today's net burn.
  • Default alive means revenue overtakes expenses before the cash runs out at the current growth rates; default dead means it does not, so the company needs new funding or changes.

Runway: 12.0 months cash runs out before revenue covers costs: default dead

Today
Show the breakdownPer month
Cash in the banktotal$1,200,000
Revenue$20,000
Expenses (gross burn)−$120,000
Net burn$100,000

Cash month by month

MonthRevenueExpensesNet burnCash at month end
1$20,000$120,000$100,000$1,100,000
2$20,000$120,000$100,000$1,000,000
3$20,000$120,000$100,000$900,000
4$20,000$120,000$100,000$800,000
5$20,000$120,000$100,000$700,000
6$20,000$120,000$100,000$600,000
7$20,000$120,000$100,000$500,000
8$20,000$120,000$100,000$400,000
9$20,000$120,000$100,000$300,000
10$20,000$120,000$100,000$200,000
11$20,000$120,000$100,000$100,000
12$20,000$120,000$100,000$0
13$20,000$120,000$100,000−$100,000

12.0 months

cash runs out before revenue covers costs: default dead

How it's calculated

Runway is how long your cash lasts. Each month, cash falls by the net burn: what you spend minus the cash revenue you collect. With no growth, runway is simply cash ÷ net burn. When revenue or costs are growing, the burn changes every month, so the calculator steps through each month until the cash runs out, or for up to ten years.

It also answers Paul Graham's question of whether a startup is "default alive": assuming its expenses and its recent revenue growth continue, does it reach profitability on the money it has left?Paul Graham

The formula

  • Net burn = monthly expenses − monthly revenue
  • Simple runway (months) = cash ÷ net burn
  • With growth: revenuem+1 = revenuem × (1 + revenue growth), expensesm+1 = expensesm × (1 + expense growth), and cashm = cashm−1 − (expensesm − revenuem). Runway ends in the month cash goes below zero (with the part month counted).

Worked example

With $1.2 million in the bank, $20,000 of monthly revenue and $120,000 of monthly costs, net burn is $100,000 and runway is 12.0 months.

$1.2 million cash, $100,000 net burnDEFAULT DEAD
LinePer month
Cash in the bank$1,200,000
Revenue$20,000
Expenses (gross burn)-$120,000
Net burn$100,000

If revenue grows 15% a month while costs stay flat, revenue covers costs from Month 14, and the company is default alive: Yes. At 5% a month it is not: No, with runway of 12.9 months.

Assumptions and limitations

  • Cash, not accounting profit. Use revenue you actually collect and costs you actually pay in each month; annual prepayments and deferred costs shift the timing.
  • Steady growth rates. Real revenue grows unevenly, and hiring plans raise costs in steps; adjust the inputs for big planned changes.
  • No new funding. Runway assumes no further money comes in.
FAQ

Questions people ask

How do you calculate startup runway?

Runway in months = cash in the bank ÷ monthly net burn, where net burn is monthly expenses minus monthly revenue. A company with $1.2 million of cash burning $100,000 a month has 12 months of runway. If revenue or costs are growing, simulate month by month instead, which is what the calculator does.

What is the difference between gross burn and net burn?

Gross burn is everything you spend in a month. Net burn is gross burn minus the cash revenue you collect. Runway depends on net burn, because revenue offsets spending; gross burn shows how much you would spend if revenue stopped.

How much runway should a startup have?

Raising a round usually takes several months, so start fundraising while you still have a comfortable buffer of runway, and raise enough to reach the milestones that justify the next round, with time to spare. Starting late risks negotiating from a position of weakness or running out of cash mid-process.

What does default alive mean?

A startup is 'default alive' if, at its current growth and spending, it reaches profitability before it runs out of cash, and 'default dead' if not. The calculator shows whether revenue overtakes expenses before your cash is gone, given the growth rates you enter.

How can I extend my runway?

Cut spending that does not drive growth, collect cash faster (for example with annual plans paid up front), raise prices, or raise money. Small monthly changes add up: reducing net burn by 20% stretches runway by a quarter. Model each option in the calculator by changing expenses, revenue or growth.

Sources

  1. Paul GrahamDefault Alive or Default Dead? (October 2015) · retrieved 2026-10-20
  2. David Sacks, Craft VenturesThe Burn Multiple (23 April 2020) · retrieved 2026-10-20

Written by Reviewed by TODO Reviewer NameLast verified Updated

How every figure is checked: methodology.