Hill & Grade Adjusted Pace Calculator
Flat pace doesn't tell the whole story on fell, trail and mountain terrain. Use our free calculator to convert hill pace to a flat-equivalent effort, or estimate your finish time on a hilly race.
Convert Your Hill Pace
Enter a pace and a gradient to see the flat-equivalent effort — or work the other way, from a flat pace to what that effort should feel like on a hill.
Estimate Your Hilly Race Time
Enter your race distance, total ascent, total descent and a flat-equivalent goal pace (e.g. your recent 10K or half marathon pace) to get a ballpark estimate of your finish time on a hilly course.
Best suited to races up to marathon distance, where a steady effort is realistic. For ultramarathons, fatigue, fuelling and walk breaks matter more than gradient alone — see the note below.
This is a simplified estimate based on a characteristic gradient derived from your total ascent and descent — it doesn't account for technical or runnable underfoot terrain, altitude or pacing strategy. The descent curve reflects typical runners on everyday terrain. On rough, technical fell descents, footing and safety can slow you further still, so a very rocky course may run slower than this estimate. For race-specific pacing advice, get in touch.
How We Actually Pace Ultras
A formula like the one above is a useful starting point, but it can't know how you personally hold up over 50, 75 or 100km. For real ultra pacing, at Townshend Performance we use each athlete's own training run pacing — how they actually climb, descend and hold form hour after hour in training on similar terrain — to build a race-day pacing plan around them specifically, rather than a generic model.
That means factoring in things a calculator never sees: how much your climbing speed really drops late in a long run, how your legs handle repeated technical descents when tired, and how much time to realistically bank for aid stations and fuelling. It's the difference between a rough estimate and a pacing strategy you can actually race to.
The Science Behind Grade Adjusted Pace
Running uphill takes more effort than running on the flat. Gentle downhills take less, but only up to a point: beyond about −10%, braking and footing start to slow you down, and by about −18% a descent takes as much effort as the flat. For climbs, our calculator uses the energy-cost model from Minetti et al. (2002), measured on elite mountain runners. For descents, it follows Strava’s 2017 Grade Adjusted Pace model, built from heart-rate data on around six million runs, which puts the fastest gradient at about −9%, roughly 12% quicker than flat pace. Minetti’s own paper notes that the energy-cost model overstates downhill race speed by up to three times, which is why Strava replaced it.
The table below shows roughly how much slower (or faster) your pace will read on different gradients, for the same physiological effort as running 5:00/km on the flat.
| Gradient | Equivalent Pace | vs Flat 5:00/km |
|---|---|---|
| -20% | 5:18/km | +0:18 slower |
| -15% | 4:40/km | −0:20 faster |
| -10% | 4:24/km | −0:36 faster |
| -5% | 4:31/km | −0:29 faster |
| 0% | 5:00/km | Same effort |
| +5% | 6:30/km | +1:30 slower |
| +10% | 8:17/km | +3:17 slower |
| +15% | 10:18/km | +5:18 slower |
| +20% | 12:31/km | +7:31 slower |
| +25% | 14:54/km | +9:54 slower |
Want Help Pacing Your Next Hilly Race?
A calculator gets you a ballpark. A coach who has raced and won on this terrain gets you a race-day pacing strategy built around the actual course. Get in touch or explore our bespoke training plans.
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