Startup Runway Calculator

What Is the Startup Runway Calculator?

Runway is how long a startup can keep operating at its current spending rate before running out of cash -- one of the most closely watched numbers for any pre-profit company.

How to Use This Tool

Enter your current cash balance and monthly burn rate. Runway in months appears instantly.

The Formula

A Worked Example

Take a hypothetical startup with 500,000 in the bank that spends a net 40,000 per month. Dividing 500,000 by 40,000 gives 12.5 months of runway, which the tool displays with one decimal place. Those are the defaults in the calculator. If the team cuts net burn to 30,000 by pausing a hire, runway extends to about 16.7 months. The tool is deliberately simple, so it is easy to test several what-if cases in a couple of minutes.

Which Burn Number to Use

The result is only as good as the burn figure you enter. Net burn, meaning cash going out minus cash coming in, is what matters for runway. If you enter gross spending while you also have revenue, the runway will look shorter than reality. If you use last month alone, a one-time expense or a lumpy customer payment could distort it, so many founders average the last three months. The Burn Rate Calculator on this site derives a monthly figure from two cash balances if you do not have a clean number.

Input Rules

• The monthly burn rate must be greater than zero. A business with zero or negative burn is not consuming cash, so runway is not a meaningful concept and the tool asks for a valid value.
• Cash balance can be zero, which returns 0.0 months. Use actual available cash, not the total including money that is committed, restricted, or owed to suppliers.

Limits of a Flat Runway Number

The calculation assumes burn stays constant, which is almost never true. Real burn changes as you hire, as revenue grows, and as annual expenses hit. A startup that plans to double its team in six months will run out of cash much faster than the simple division shows. Consider building a month-by-month projection in a spreadsheet for planning, and use this calculator as a quick reality check on the present state.

The figure also ignores timing risk. Receivables may pay late, payroll taxes may fall due in bunches, and refunds can arrive unexpectedly. Treat the result as an optimistic ceiling, and keep a buffer.

Fundraising Timing

Raising money often takes longer than founders expect, and a company with only a few months of runway negotiates from a weaker position. Many advisors suggest starting fundraising conversations well before the cash is tight. There is no universal rule for how many months are enough, since the answer depends on your market, your traction, and investor appetite, so discuss it with mentors or advisors who know your situation.

Ways to Extend Runway

• Reduce net burn by cutting discretionary costs or deferring hires; re-enter the new burn to see the effect.
• Increase revenue or improve collections. The Days Sales Outstanding Calculator can show how slow customer payments are tying up cash.
• Add funding, then add it to the cash balance and recalculate. If the funding comes with new spending plans, raise the burn figure to match.
• Negotiate longer payment terms with suppliers where possible.

Use It Regularly

Runway is a moving figure. Recalculate monthly using fresh balances so you notice a decline in time to respond. A sudden drop in runway between two months is usually more informative than the number itself, because it means spending has accelerated or revenue has slowed. This tool is for planning and is not financial advice; discuss major decisions with your accountant or advisors.

Frequently Asked Questions