Grade Adjusted Pace (GAP) Calculator
Convert any uphill or downhill pace into its flat equivalent, find the pace to hold on a slope, turn a treadmill incline into outdoor effort and plan a hilly route.
Grade adjusted pace (GAP) tells you what a pace run on a slope is worth on flat ground. A given pace on a steep climb is a far bigger effort than the same pace on the flat, and a gentle descent costs less. Pick what you want to know and type your numbers: the result updates as you go. You get your flat equivalent pace, the pace to hold on a slope, the treadmill speed that matches an outdoor effort, or the time of every climb and descent of a route, plus the pace of the same effort at every grade from -15 % to +25 %.
What do you want to know?
You ran a pace on a slope. This gives the flat pace of the same effort.
Use a minus sign for a descent, for example -6.
Enter your values to see your result. It updates as you type.
How the calculation works
Running uphill costs more energy per metre and running downhill costs less, up to a point. GAP turns that cost into a pace: it is the flat pace that would cost the same effort as your pace on the slope.
Uphill: the Minetti energy cost
For climbs we use the energy cost of running measured by Minetti and colleagues (2002) on slopes up to 45 %. On a +10 % grade the cost per metre is about 1.66 times the flat, so 6:00 per km there is worth about 3:37 per km on the flat. At +5 % the same effort is about 30 % slower in pace, at +3 % about 17 %.
Downhill: a capped gain
Minetti's curve says a descent of around -10 % should make running much cheaper, more than any runner can use: braking, foot placement and the load on the quads limit the speed. We cap the gain at about 12 % around -9 %, bring it back to nothing at -18 % and add a cost beyond that. This is the shape seen in Strava's 2017 heart rate based GAP model, not a pure physics result.
Treadmill: the 1 % rule
A treadmill belt removes air resistance, so a 1 % incline reproduces the cost of flat outdoor running (Jones and Doust, 1996). The calculator therefore treats the incline minus one point as the outdoor grade. It is most valid between about 10.5 and 18 km/h, and less so for slow jogging or sprinting.
Routes: segment by segment
For a route, each segment gets the pace for its own grade from your flat effort, then the times are added up and compared with the same distance on the flat. It is the building block of a trail time estimate, but a real race adds fatigue, technical ground, altitude and walking on the steepest climbs.
What GAP does not tell you
GAP is an average for a runner on a smooth surface. It ignores heat, wind, altitude, technical terrain, fatigue and your own strengths on climbs or descents. Use it to compare efforts and to set a starting pace, then let heart rate and feel decide.
Related Tools
Scientific references
- Minetti AE, Moia C, Roi GS, Susta D, Ferretti G. (2002). Energy cost of walking and running at extreme uphill and downhill slopes. Journal of Applied Physiology, 93(3):1039-1046.
- Jones AM, Doust JH. (1996). A 1% treadmill grade most accurately reflects the energetic cost of outdoor running. Journal of Sports Sciences, 14(4):321-327.
- Margaria R, Cerretelli P, Aghemo P, Sassi G. (1963). Energy cost of running. Journal of Applied Physiology, 18(2):367-370.
- Vernillo G, Giandolini M, Edwards WB, et al. (2017). Biomechanics and physiology of uphill and downhill running. Sports Medicine, 47(4):615-629.
Frequently asked questions
What is grade adjusted pace (GAP)?
Grade adjusted pace is the flat pace that would cost you the same effort as the pace you ran on a slope. It lets you compare a hilly run with a flat one: a slow pace on a steep climb can be the same effort as a much faster pace on the flat.
How much does a hill slow me down?
At the same effort, a +3 % grade costs about 17 % in pace, +5 % about 30 % and +10 % about 66 %. A 6:00 per km pace on a +10 % climb is worth about 3:37 per km on the flat. Use the pace table under the result to read any grade from -15 % to +25 %.
How does treadmill incline compare with running outside?
At a 1 % incline a treadmill matches the effort of flat outdoor running, because the belt removes air resistance. At 0 % it is easier than outside. Above 1 % each extra point of incline is harder, in line with the same slope outdoors. Enter your speed and incline in treadmill mode to see your outdoor flat pace.
Does running downhill make me faster by the same amount?
No. Downhill helps less than uphill hurts. Gentle descents give a gain of up to about 12 % in pace, around -9 %. Steeper than about -18 % the gain is gone and braking and impact cost effort again, so GAP does not scale in a straight line downhill.
Is this the same as Strava GAP?
No. Strava's GAP is a different model, built from heart rate data. This calculator uses published energy cost data for climbs with a capped downhill gain, so numbers can differ by some seconds per km. Use either one to compare efforts, not as an exact measure of your physiology.