Racing · Free tool
Grade Adjusted Pace (GAP) Calculator
Running uphill at your flat pace is a much harder effort. Running downhill at it is easier, but only up to a point. Enter a pace and a gradient to see the pace that matches your flat effort on that hill, or turn the pace from a hilly run back into the flat pace it was worth.
How the adjustment works
Uphill, the cost rises quickly: at the same effort you run about 22% slower on a 5% grade and about 55% slower on a 10% grade. Downhill, the help is smaller than most people expect. It peaks at around 14% faster on a grade near −8%, and by about −16% a descent is no faster than the flat, because more of every stride goes into braking.
We use the curve ultraPacer fitted to real-world data, which closely follows the model Strava switched to in 2017 after studying its runners’ heart rates. Older models built on laboratory energy measurements predicted runners could go nearly twice as fast down steep hills, and nobody actually does.
Using it in a race
Run hills by effort, not by pace. Use the table to see how much slower a climb is allowed to be, and resist chasing your flat pace up it. The time you give up by easing off on a climb is small; the damage from going too hard there shows up later in the race.
On steep trail climbs, somewhere past 15 to 20%, most runners are as fast hiking as running, for far less effort. On descents, take what gravity gives you without hammering your quads, especially early in a long race.
Why your watch may say something different
Apps use different models, and GPS elevation is noisy, so two apps can give the same run different grade-adjusted paces. Averages hide detail too: because steep sections cost more than their share, a climb that alternates steep and flat is harder than its average grade suggests.
Frequently asked questions
What is grade adjusted pace?
Grade adjusted pace (GAP) is the pace you would have run on flat ground for the same effort. It lets you compare a hilly run with a flat one, and it is the fairest way to judge easy runs and workouts on rolling routes.
How much slower should I run uphill?
At the same effort, about 20% slower on a 5% grade and about 55% slower on a 10% grade. A runner at 5:00/km on the flat would be at about 6:07/km and 7:45/km respectively.
Is running downhill faster?
Only on gentle descents. The biggest benefit, about 14% faster than flat, comes at around −8%. Steeper than about −16%, braking cancels out the help from gravity, and your pace at the same effort is back to flat or slower.