Free web app for calculating grade-adjusted paces (GAP) for running hill workouts

I’m happy to announce that my new web app for calculating effective paces for uphill and downhill running is now live!

⛰️ Check out my new GAP calculator here!

This free app lets you calculate paces for uphill and downhill running, even on very steep hills.

My pace percentage calculator for percentage-based workouts has been a huge hit, and I'm excited to put out another calculator to help with training and racing.

The calculations in my GAP app are based on metabolic data collected from two scientific studies: Black et al 2018 and Minetti et al 2002. Under the hood, the app compares flat-ground and incline or decline running by calculating the expected metabolic cost as a VO2.

The Minetti study includes data from very steep inclines and declines, so the GAP calculator works for grades as steep as +50% and -50%!

You can see how a given flat-ground effort translates to hills—for example, “If I run at 6:00/mi flat-ground effort up a 3% grade, how fast will I go?”—and you can also see how your actual pace on an uphill or downhills translates to expected flat-ground pace—for example, “I split 8:20 for a mile that gained 130 feet, what flat-ground effort was I running?”

The app supports inputting hill data as grade, slope, rise over run, or vertical speed, and supports a number of pace and speed settings (e.g. km/hr for European treadmills). You can easily input a pace and convert the GAP to speed as well.

Check out the extensive How to Use section to see the details on how it works, plus some of the limitations of metabolically-based GAP calculations. 

You can bookmark this web app for future use, and if you’re an iPhone or iPad user, you can even create a custom shortcut to save a link to it on your home screen. 

A few of my athletes have given this calculator a spin already and have reported good results. I’d love to hear what you think of it too! If you find any bugs, or if you’ve got feedback, drop me a line

Get updates

If you haven’t already, sign up below for my email list–it’s the best way to find out when I launch new projects like this gap app (and I've got several more projects like this that I'm working on!). I'll also be able to let you know when I make major upgrades, like when I added treadmill speed support for my pace percentage calculator.

About the Author

John J Davis, PhD

I have been coaching runners and writing about training and injuries for over ten years. I've helped total novices, NXN-qualifying high schoolers, elite-field competitors at major marathons, and runners everywhere in between. I have a Ph.D. in Human Performance, and I do scientific research focused on the biomechanics of overuse injuries in runners. I published my first book, Modern Training and Physiology for Middle and Long-Distance Runners, in 2013.

3 thoughts on “Free web app for calculating grade-adjusted paces (GAP) for running hill workouts”

  1. Hi John,
    Awesome calculator, I've been looking for something with this level of detail in the notes!
    Question: how use this calculator to account for a varied incline profile? Say you run 5% for 5min, then 10% for 5min, then decline 5% for 10min, etc... how should one calculate the overall "flat" equivalent? Average all the inclines over their time or distance? or?
    I understand Strava and Garmin can do this for you, but I like to check the numbers myself...

    • Hi Mike, glad you found it useful! For now, you'll have to break up the run chunk-by-chunk. Eventually I might be able to code up something where you can upload a route from your watch and get a point-by-point GAP estimate, like Strava or Garmin will do, but that would require a more complicated setup!

  2. Glad to have this calculator! I've been training for half and full marathons for months, completing some races. Next up is a 17km trail race. Excited to see how your calculated time compares to my real-world result.

    Thank you!


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