What is grade-adjusted pace (GAP)?
The flat-ground pace that would cost the same effort as the pace you actually ran on a hill. It lets you compare a hilly run with a flat one honestly.
Running uphill costs more energy per metre than running on the flat, and running downhill costs less — though not by nearly as much as the climb costs. Grade-adjusted pace applies that known cost relationship to convert your actual pace on a gradient into the equivalent flat-ground pace at the same metabolic cost.
The practical use is comparison. A 5:30/km on a 4% climb is a much harder effort than 5:30/km on the flat, and without adjustment your training log tells you the two runs were identical. GAP lets you run by effort on rolling terrain while still hitting a meaningful intensity target, and it makes hilly and flat sessions comparable in the same log.
The asymmetry is the part most runners underestimate. Because the uphill penalty is much larger than the downhill saving, a rolling out-and-back course is slower than a flat one of the same distance even though you climb and descend equally. This is why net-downhill courses help less than expected, and why an undulating course is genuinely harder than its elevation summary suggests.
On this site the adjustment uses the Minetti gradient-cost polynomial, and it drives the split tables on every marathon course page — so the pacing plan for a hilly course reflects what each kilometre will actually cost you rather than dividing the distance evenly.
Key numbers
| Model | Minetti et al. 2002 | gradient cost polynomial |
|---|---|---|
| Valid range | −45% to +45% | gradient |
| Key property | uphill cost > downhill saving |
Work it out for yourself
Marathon course profiles — See grade-adjusted split tables for 32 marathon courses at any goal time.
Frequently asked questions
Is grade-adjusted pace accurate?
The underlying cost curve is well measured, so the metabolic adjustment is sound. What it does not capture is the muscle damage from sustained descent or the fatigue asymmetry between climbing and descending, so GAP is an energy-cost equivalence rather than a complete difficulty equivalence.
Should I train by grade-adjusted pace?
It is a good way to hold the right effort on rolling terrain, particularly for threshold and marathon-pace sessions where the intensity matters more than the number on the watch. For races on flat courses, raw pace is what you are being scored on.
Sources
- Minetti et al. (2002). Energy cost of walking and running at extreme uphill and downhill slopes. Journal of Applied Physiology.
- Vernillo et al. (2017). Biomechanics and physiology of uphill and downhill running. Sports Medicine.
Related explainers
Glossary: GAP (Grade-Adjusted Pace), Minetti Gradient Cost