Think of an airplane on a runway. It has a limited amount of pavement to build up enough speed for takeoff. If the runway is too short, the plane can't get airborne and will run out of room. A startup's financial runway is a similar concept. It's the amount of time your company has before it runs out of money.

This metric isn't just a number on a spreadsheet; it's a measure of your startup's lifespan. Knowing your runway helps you make critical decisions, plan for the future, and understand when you might need to secure more funding. It answers the most fundamental question for any new business: How long can we keep the lights on?

Calculating your runway requires just two pieces of information: how much money you have and how quickly you're spending it.

First, let's look at cash reserves. This is straightforward. It’s the cash in your company’s bank accounts. For this calculation, you want to focus on liquid assets that you can access immediately. Don't include money you're expecting to receive soon (like accounts receivable) unless you are absolutely certain it will arrive. The goal is to get a realistic picture of the cash you have on hand right now.

Next is your monthly burn rate. This is the speed at which your company is spending its capital. If your company isn't yet profitable, you have a burn rate. It represents the negative cash flow of the business each month.

To find your burn rate, you subtract your total monthly revenue from your total monthly expenses. For example, if your company spends $50,000 in a month on salaries, rent, and marketing, and brings in $10,000 in revenue, your net burn for that month is $40,000.

Once you know your cash reserves and your monthly burn rate, calculating your runway is simple. You just divide your total cash by your monthly burn.

Let's walk through an example. Imagine a startup has $400,000 in the bank. After analyzing their finances, they determine their monthly burn rate is $50,000. Here’s the calculation:

This startup has 8 months of runway. That means if nothing changes with their income or expenses, they have eight months to either become profitable or find additional funding before they run out of money.

Ready to test your understanding?

Understanding runway is a foundational skill for anyone involved in a startup. It's the clock that every founder is racing against.