The only rucking calorie calculator you’ll ever need, backed by military science

Use this exclusive calculator to determine your burn.

“How many calories do I burn rucking?”

This question fills my inbox. People message me their body weight, pace, vest or pack weight—the works—and ask me for an exact number.

I wanted to help everyone, but being a human activity tracker got time-consuming fast.

The solution: I worked with military researchers to access a rucking calorie burn calculator.

It’s built on a formula you can’t just find online and is based on years of military research. It’s the most accurate one in existence, and it works for backpacks and vests. It also accounts for variables most other calculators ignore.

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Here’s today’s roadmap:

• The science of rucking calorie burn: Why this calculator is the most accurate to date.

• How I got the calculator: Insights from top U.S. military researchers.

• How to use the calculator: Detailed step-by-step instructions to get the most from the tool.

• The calculator: Plug in your numbers, get your accurate results.

The science of rucking calorie burn

For a long time, scientists made educated guesses about calorie burn using various equations. But they weren’t perfect. Calculating calorie burn from weighted walking is challenging because:

• It’s a rather understudied form of exercise.

• It mixes strength and cardio.

• It includes many factors that impact calorie burn. For example, the weight in your pack or vest, the terrain you’re walking on, and more.

• It also has a muscular effect. It will lead you to burn more fat and build or maintain muscle, and your improved body composition will likely have longer-term calorie-burning effects.

For example, the popular Pandolf equation, which scientists used for years, was recently found to underestimate calorie burn. Another problem: most calorie burn estimators were based entirely on male soldiers, making them biased and off-base for half of the population.

Then David Looney changed the game.

Looney is a mathematical physiologist who conducts research with the Department of Defense and U.S. Army Research Institute of Environmental Medicine (USARIEM). He published a study in the journal Medicine & Science in Sports & Exercise that developed the most accurate calculator for determining the number of calories burned from walking with weight.

It’s important to note that Looney’s study included more women than previous studies. Military research has traditionally focused predominantly on men, even though more women are now entering the military. Not to mention that far more civilian women are walking with weight to improve their health and fitness.

This means that the calorie burn figures from those old studies may not apply to all people. His model is the best existing estimate of the calories we’ll burn walking with weight.

For my upcoming book, Walk with Weight, I was able to get my hands on the calculator. This required breaking various classified protocols and using methods that were entirely at odds with the Geneva Conventions (I’m kidding. Maybe.).

Now I’m sharing it below.

In the rest of this letter, you’ll get:

• The only rucking calorie calculator you’ll ever need, backed by military science

• A detailed, step-by-step walkthrough on how to input your numbers to get your exact calorie burn.

The calculator: How to use it

Substack’s format is beautiful in its simplicity. But it’s also so simple that I couldn’t embed the calculator into this post.

Click this button to get the calculator.

That will instantly download an Excel spreadsheet. If you don’t have Excel, open it in Google Sheets or Numbers.

Step 1: Enter your bodyweight

Input how much you weigh in pounds. If you typically use kilograms, convert KG to LBS using an online calculator.

Step 2: Enter your pack or vest weight as a percentage of your bodyweight

Why are we using percent of bodyweight instead of the weight of the pack or vest (e.g., 30lbs)?

Because different loads impact people differently. Rucking with 30lbs is far more demanding for a 100-pound person than it is for a 200-pound person. By using load as a percentage of bodyweight, we get more accurate data.

• So, for example, if you weigh 150 pounds and you walked with 30 pounds (20 percent of your bodyweight), you’d enter 20% in the “Pack or Vest Load” column.

• If you can’t figure out the weight as a percentage of your bodyweight in your head, use the middle calculator on this page. I.e., add your info to the “BLANK is what % of BLANK” form. In our example above, you’d input your pack weight of 30 into the first blank and your bodyweight of 150 into the second blank.

Step 3: Enter your walking speed in MPH

You can determine this by figuring out how long it takes you to walk a mile. Here are some quick reference figures:

• 2 MPH = 30 minute mile

• 2.5 MPH = 24 minute mile

• 3 MPH = 20 minute mile

• 3.5 MPH = 17 minute mile

• 4 MPH = 15 minute mile

• 4.5 MPH = 13:20 minute mile

• Note 1: The average walking speed for an active person is around 3.5 MPH.

• Note 2: GPS apps like Strava will tell you the average mile pace of your walk.

Step 4: Enter the grade of your route

This is how hilly your walk was.

If your walk was flat, use 1%. If your walk was hilly, use your best guess of the average grade you walked. If you’re walking a loop—e.g., starting and ending at the same place—use 1%.

Step 5: Enter your walking surface

Use the drop-down tool to choose your terrain type (pavement, gravel, etc). If you’re walking a trail, use gravel.

Step 6: Get your number

Yes, it requires a few inputs. But calorie burn from rucking is complicated. Your bodyweight, pack weight, speed, terrain, and slope all matter.

This calculator accounts for all of it. Which is why it’s the most accurate one available.

Have fun, don’t die, ruck on,

Michael