Startup Runway Calculator
Startup runway is the single number every founder watches: how many months the business can keep operating before the cash runs out. It is built from three figures you already track, the cash on hand, the monthly expenses and the monthly revenue. The calculator first works out net monthly burn, which is expenses minus revenue, the real amount of cash the company loses each month once income is counted. It then divides the cash on hand by that net burn to give the runway in months, and converts it to years so you can see the bigger picture at a glance. If revenue covers expenses, net burn is zero or negative and the business is cash-flow positive, so there is no finite runway; the tool reports that clearly rather than showing a misleading figure. All three inputs are fully editable, so you can stress-test a hiring plan, a price change or a slower sales month in seconds. The US Securities and Exchange Commission explains cash flow and reading financial statements through its Investor.gov education site. Every result here is computed deterministically from the standard formula, shown in full below, with a worked example that reconciles exactly to the calculator so you can follow each step.
Runway is cash on hand / net monthly burn. With $500,000 of cash and a net burn of $40,000 a month (60,000 expenses less 20,000 revenue), the runway is 12.50 months.
Startup runway formula
net monthly burn = monthly expenses - monthly revenue
runway (months) = cash on hand / net monthly burn
runway (years) = runway in months / 12
if net burn is zero or below: business is cash-flow positive, no finite runway
Net burn captures how much cash the company truly loses each month after revenue. Dividing the cash balance by that burn gives the number of months the business can run before the money is gone. When revenue covers costs, there is no burn to divide by.
Worked example
A startup holds 500,000 in cash, spends 60,000 a month and earns 20,000 a month in revenue.
- Net monthly burn = 60,000 - 20,000 = 40,000
- Runway in months = 500,000 / 40,000 = 12.50 months
- Runway in years = 12.50 / 12 = 1.04 years
So the business has 12.50 months, about 1.04 years, of cash left at the current rate. These are the calculator's default inputs, so the results above match the widget exactly.
Months of runway at different burn rates
With 500,000 in cash, a lower net burn stretches the runway. This table shows the effect of changing only the net monthly burn.
| Net monthly burn | Runway (months) | Runway (years) |
|---|---|---|
| 20,000 | 25.00 | 2.08 |
| 30,000 | 16.67 | 1.39 |
| 40,000 | 12.50 | 1.04 |
| 60,000 | 8.33 | 0.69 |
| 100,000 | 5.00 | 0.42 |
Cash flow and reading financial statements: US Securities and Exchange Commission, Investor.gov.
Startup runway calculator: frequently asked questions
What is startup runway?
Startup runway is the number of months a business can keep operating before it runs out of cash, assuming spending and income stay roughly the same. You take the cash on hand and divide it by the net monthly burn, the amount the company loses each month after revenue. A runway of 12 months means the firm has a year of cash left at the current rate, a key figure for founders planning when to raise more money or reach break-even.
What is net monthly burn?
Net monthly burn is monthly operating expenses minus monthly revenue. It is the real cash the business consumes each month once income is counted. If expenses are 60,000 and revenue is 20,000, net burn is 40,000 a month. Gross burn, by contrast, looks only at total spending and ignores any incoming revenue, so net burn gives a truer picture of how fast cash actually drains.
What happens if revenue covers expenses?
If monthly revenue equals or exceeds monthly expenses, net burn is zero or negative and the business is cash-flow positive. In that case there is no finite runway: the company is adding to its cash balance rather than depleting it. This calculator detects that situation and reports that the business is cash-flow positive instead of showing a misleading runway number.
How much runway should a startup keep?
Many investors suggest keeping at least 12 to 18 months of runway after a funding round, because raising capital takes time and rarely goes exactly to plan. The right buffer depends on how predictable the revenue is and how long the next milestone will take. A shrinking runway is a prompt to cut costs, lift revenue or start a raise well before cash runs low.
Does this calculator account for changing burn?
No. It assumes a steady net monthly burn, which is the simplest and most common way to estimate runway. In reality spending and revenue shift over time, so the figure is a snapshot at today's rate rather than a forecast. Update the inputs whenever your numbers change, and treat the result as a planning guide rather than a precise prediction.
Official sources
- Cash flow, burn and reading financial statements: US Securities and Exchange Commission, Investor.gov. As at 24 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 24 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.