Grade-Adjusted Pace (GAP) Calculator
Enter your actual pace on a hill and the grade, and this converts it into the flat-equivalent pace that represents the same physical effort — so you can compare hilly and flat runs fairly.
Equivalent-effort pace at other grades
How this is calculated
Grade-adjusted pace isn't a fixed penalty per percent of grade — it's based on how much more (or less) energy running actually costs at a given slope. This calculator uses the Minetti et al. (2002) running-economy model, a polynomial fit to treadmill data measuring the metabolic cost of running across grades from -45% to +45%, which is why it stays reasonably accurate well beyond typical road grades rather than breaking down at steeper trail pitches.
The model gives an energy cost per kilogram per meter at any grade. Your actual pace and that cost together imply a metabolic power output (cost × speed). The flat-equivalent pace is the speed at 0% grade that would require that same power output — in other words, the pace you'd be running if the same effort were spent on flat ground instead of the hill.
Downhill grades aren't simply 'free speed' in this model either: running economy actually improves on moderate downhills (lower cost per meter) before cost rises again on very steep descents due to braking forces — so a fast downhill split can represent meaningfully less effort than the same pace on flat ground, which the adjustment reflects directly rather than ignoring.
The reference table shows what the same effort would look like at a few other common grades, using the same underlying cost ratio — useful for comparing splits across a rolling course, not just converting a single number.
Frequently asked questions
What is grade-adjusted pace actually for?
It lets you compare runs on different terrain fairly. A 7:30/km pace on a 6% uphill grade and an 8:10/km pace on flat ground can represent nearly identical effort — raw pace alone hides that, grade-adjusted pace reveals it.
Why isn't the adjustment just a fixed amount per percent of grade?
Because the real energy cost of running against gravity isn't linear with grade — it curves, especially at steeper slopes, and downhill running has its own non-linear cost curve (easier at moderate grades, harder again at very steep ones). A fixed per-percent rule of thumb gets this visibly wrong outside gentle grades, which is why this uses the full Minetti polynomial instead.
Does this account for trail surface (not just slope)?
No — it models grade only, the way most GAP tools do. Loose gravel, mud, singletrack technicality and altitude all add real cost on top of grade that this doesn't capture. Treat the result as the grade-only component of the difference.
Is this the same formula Strava and other apps use?
Several GAP implementations across the running-tech world are built on the same Minetti et al. (2002) economy-of-running data, though exact implementations vary in range limits and rounding — small differences between tools for the same inputs are normal.
Sources
- Minetti, A.E., Moia, C., Roi, G.S., Susta, D., Ferretti, G. (2002) — 'Energy cost of walking and running at extreme uphill and downhill slopes', Journal of Applied Physiology
- runningwritings.com — grade-adjusted pace methodology and worked examples
Related calculators
Disclaimer
This is a physiological model fit to group treadmill data (measured at 1.8-12.6 km/h), not a measurement of your individual economy — actual grade tolerance varies by runner, surface, and fitness, and faster paces extrapolate slightly beyond the study's directly-measured speed range. Treat the result as a useful estimate for comparing efforts, not an exact substitute for how a specific hill will feel.
Last updated 2026-11-05.