5 min read

The Difference Between Burn Rate and Runway: A Pilot’s Perspective

Running a business is a lot like flying an aircraft.

Your mission is simple: Achieve lift (or, in business terms, profitability). But before you can start soaring, you need to survive the most dangerous stage: takeoff.

There’s a sobering parallel here: 20% of startups fail in their first year. And coincidentally, the same percentage of all general aviation accidents occur during takeoff.

Whether you’re in the first year of running a business or a long-time veteran, the fight for liftoff hinges on understanding two critical concepts:

(1) Burn rate, the speed at which you’re burning through your capital reserves, and (2) runway, how much room you have left in those reserves (and thus how many more months you can operate before running out of cash).

But just knowing these numbers won’t get you safely airborne.

As in aviation, the real value doesn’t come from simply memorizing metrics—it comes from understanding how to use them in charting a safe, successful ascent.

Burn Rate and Runway: A Quick Breakdown

Before you can achieve lift, you need to know whether your runway is long enough to build momentum.

While we’ve defined burn rate and runway in broad terms, it often makes more sense to look at it through formulas:

  • Burn rate = monthly operating costs
  • Runway = total capital ÷ burn rate

So, if you’re looking at a burn rate (net monthly expenses) of $100k, and you’ve got $600k left in the bank as capital, then you’ve got a 6-month runway.

Of course, this is a simplified model, and one that doesn’t take revenue into account (there’s a reason for that, which I will speak to in a minute).

First, we need to clarify why these numbers matter. Or rather, why they don’t matter—at least, not as much as you might think.

Types of Takeoffs: The Modern Runway in Practice

Just as a commercial airliner’s takeoff will differ vastly from that of an F-18 fighter jet, your takeoff phase may look very different depending on the type of business you’re running.

Consider two examples:

  1. SaaS businesses uniquely grow from a loss position. Raising capital, riding negative cash flow through Series A–C, and banking on revenue recognition later… Every dollar matters. Your burn rate is constantly shifting, and runway can disappear faster than expected.
  2. Aerospace and defense contractors operate on long-term strategy. With high upfront R&D costs and possibly years from winning a contract to seeing the paycheck, runway calculations must ensure you’ve got enough fuel in the tank to make the journey in between.

In both cases, revenue doesn’t tell the full story month-over-month.

SaaS will only recognize that revenue later down the line, once customers are locked in; A&D teams often endure long dry spells before seeing sudden revenue spikes.

This is why I excluded revenue from the earlier burn rate and runway examples. Even for more ‘traditional’ businesses, standard calculation methods may hide financial turbulence.

For example, a calm three-month average net burn could mask a cash-hungry quarter lurking around the corner, filled with:

  • Annual insurances, subscriptions, or other renewal costs
  • Employee hiring sprees or bonus payouts
  • Bulk or seasonal inventory restocks

Without eyes forward on what’s coming (and projections for what could be coming), burn rate becomes little more than a rear-view metric.

And a runway that looks long in hindsight may, in reality, be far shorter than you think.

Achieve Altitude with a Fractional CFO Co-Pilot

Running a mid-market business feels like a daily catapult shot, going from 0 to 140 MPH in two seconds, with little margin for error.

(As both a former pilot and current business owner, I can tell you: margin matters.)

With a minimal runway, even the slightest variables—ordnance weight, fuel load, wind conditions—can make the difference between a successful takeoff and a very expensive early landing.

The same is true with your business.

Just like pilots never push the throttle without first computing takeoff data, forward-thinking leaders never make critical decisions without running the numbers. That info helps you see, not just how far you can go, but how you can maximize your chances of going airborne—before the runway runs out.

Easier said than done? Absolutely.

Which is why I recommend partnering with a fractional finance firm like Quadrant Advisory.

Rather than peddle general advice, our fractional CFOs help you prepare for takeoff by equipping you with razor-sharp financial insights specific to your industry, business, and situation.

If you’re interested in how it works, book a call with me. Let’s see how we can help your business achieve takeoff.

Sources:

Forbes Advisor. What Percentage Of Startups Fail? https://www.forbes.com/advisor/business/software/startups-failure-rate/

Federal Aviation Administration. Airplane Flying Handbook (3C) Chapter 6

https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/airplane_handbook/07_afh_ch6.pdf