Average GAP (Grade Adjusted Pace): what it is and how to read it on Strava
You finish your trail run, open Strava, and there it is — between cadence, heart rate and elevation — a number that catches your eye: Avg GAP. 4:52/km. While your actual pace shows 5:38/km. What is going on? Did you run faster than you thought? Is your watch glitching? Neither. GAP, or Grade Adjusted Pace, is one of the most useful — and most misunderstood — metrics in modern running. This guide explains exactly what average GAP is, how it is calculated, how to read it on Strava, and how to use it to improve your training.Key takeaways
- Average GAP is your equivalent flat-ground pace, accounting for the elevation changes in your run.
- It is calculated using Minetti’s physiological model of the energy cost of locomotion on slopes.
- On Strava, it appears in the “Analysis” section for all running activities, and in the main stats for hilly routes.
- A solid GAP sits between 4:30 and 6:00/km for most regular runners, depending on level and terrain.
GAP: full definition (Grade Adjusted Pace)
GAP stands for Grade Adjusted Pace — known as VAP (Vitesse Ajustée selon la Pente) in French. It is an estimate of the pace you would have held if your route had been perfectly flat, at the same physical effort.
Why do we need this? Because running uphill costs far more energy than running on flat ground at the same speed. When you climb a 10% incline at 7 km/h, your body is working as hard as if you were running much faster on flat terrain. GAP normalises that effort — it erases the elevation to give you a comparable pace value across different runs.
GAP vs actual pace: what is the difference?
Actual pace is what your GPS records: the time taken to cover each kilometre. It depends directly on your physical speed on the terrain. GAP interprets that speed through the lens of gradient.
In practice:
- Uphill: your GAP is faster than your actual pace. You are physically moving slower, but expending as much energy as a faster runner on flat ground.
- Downhill: your GAP is slower than your actual pace. Gravity helps you move, so your real effort is lower than your speed suggests.
- Flat: GAP and actual pace are identical.
Concrete example: you climb a 10% hill over 1 km at an actual pace of 6:30/km. Your GAP for that kilometre will be around 4:45/km — the pace at which you would have run on flat ground to expend the same energy.
Average GAP vs average pace on Strava: two different metrics
Average pace on Strava is the arithmetic mean of your speed across the whole run: total distance divided by moving time. It reflects your real physical speed.
Average GAP is the mean of your grade-adjusted paces, calculated metre by metre throughout the activity. On flat terrain, the two are identical. On hilly terrain, the gap between them can reach 30 to 60 seconds per kilometre — or more on trail runs.
When comparing two runs on different types of terrain, average GAP is always more meaningful than average pace.
How is GAP calculated? The Minetti model
GAP is not magic: it rests on solid scientific foundations established by Professor Alberto Minetti, physiologist at the University of Milan. His work published in the Journal of Applied Physiology demonstrated that the energy cost of locomotion varies non-linearly with slope.
The base formula
Minetti’s equation models the energy cost C (in J/kg/m) as a function of slope i (expressed as a decimal fraction):
C = 155.4 × i⁵ − 30.4 × i⁴ − 43.3 × i³ + 46.3 × i² + 19.5 × i + 3.6
In plain English: the steeper the slope, the higher the energy cost — and the relationship is not proportional. A 15% gradient does not cost three times more than a 5% one. The ratio is considerably higher.
Strava, Runalyze and most analysis tools rely on this model (or an improved variant) to calculate GAP in real time, GPS point by GPS point.
Why downhill is treated differently
Downhill physics are asymmetric. Up to around -10% gradient, gravity helps you go faster without extra effort. Beyond that, your muscles must actively brake against acceleration, which costs energy. Running down a -30% slope is exhausting, even at high speed.
Strava confirmed this through its own athlete data: the downhill adjustment caps at around -10% incline. Beyond that, the GAP correction stabilises. This is why your GAP on a very steep descent can seem paradoxically high — the algorithm recognises that you are expending more energy than a gentle descent would suggest.
Note also: GAP does not account for terrain technicality (rocks, roots, mud) or weather conditions. It is an energy estimate, not a measure of overall difficulty.
How to read your average GAP on Strava
Good news: Strava displays GAP natively, with no setup required. The display varies by platform and activity type.
On mobile
Open your running activity in the Strava app and scroll down to the detailed stats. Average GAP appears:
- For hilly runs (trail, routes with significant elevation): directly in the main stats, next to pace and elevation.
- For all runs: in the “Analysis” section further down. It is shown as a graph (GAP vs actual pace) with the overall average value.
On Strava segments, the segment GAP is displayed next to your time and actual pace — very useful for comparing efforts on the same segment under different conditions.
On desktop / web
On the Strava website, open your activity and click the “Analysis” tab. You will see a graph overlaying actual pace and GAP across the run. The overall average GAP is shown at the top of the analysis panel.
Desktop offers the richest reading: you can zoom into specific segments, see the GAP/actual pace gap on each section, and identify where your effort management was optimal — or where you pushed too hard on the descents.
Segment GAP vs overall GAP
Overall average GAP gives a big-picture view of your run. It is useful for comparing similar outings on different routes.
Per-segment or per-kilometre GAP is the fine analysis tool. It shows whether you managed your effort consistently (stable GAP = good pacing) or sprinted uphill then coasted downhill (highly variable GAP = poor management on ultras or long runs).
What is a good average GAP for your level?
This is the most frequently asked question — and the least well documented online. Here are reference values.
GAP reads like a per-kilometre pace (min/km). The lower the number, the faster you are. It is directly comparable to your road or track pace, which makes it intuitive once you grasp the concept.
Reference table by runner level
| Level | 10km road pace | Avg GAP — long trail run | Avg GAP — hilly road run |
|---|---|---|---|
| Beginner | 6:30 – 7:30/km | 7:00 – 8:30/km | 6:30 – 7:30/km |
| Regular runner | 5:00 – 6:30/km | 5:30 – 7:00/km | 5:00 – 6:30/km |
| Intermediate | 4:00 – 5:00/km | 4:30 – 5:30/km | 4:00 – 5:00/km |
| Advanced | 3:20 – 4:00/km | 3:45 – 4:30/km | 3:20 – 4:00/km |
These are benchmarks, not absolute truths. Two key points to keep in mind: the type of run matters (a 6:00/km GAP on an easy recovery jog is excellent; the same on a tempo session is too slow), and progression is always measured against yourself, not others.
Trail GAP vs road GAP: why the gap widens
On road or track, your average GAP will be very close to your actual pace — unless the route has significant elevation (think London’s undulating course or certain hilly half marathons).
In trail, the difference can be massive. On an ultra with 2,000m of positive elevation over 50 km, your actual pace might be 8:30/km while your average GAP hovers around 6:00/km. That is not cheating — it means your overall effort corresponds to that of a runner holding 6:00/km on flat ground. Useful for coaches, organisers, and your own ego after a brutal day in the mountains.
How to use GAP in your training
Knowing your GAP is good. Using it to improve is better. Here are two concrete use cases rarely covered elsewhere.
Long run on hilly terrain: GAP as your effort compass
On a long run (90 minutes and over), the classic trap is going too hard uphill — and blowing up before the finish. GAP solves this elegantly.
The approach: set a target GAP range for your long run (typically your easy aerobic pace, around 65-75% of your 10km pace), then configure your watch to display GAP in real time (available natively on Garmin, COROS and Apple Watch, or via third-party apps).
Result: on climbs you naturally slow down (keeping your GAP within the target range), and on descents you can open up slightly while staying in your effort zone. You finish the run fresh and consistent, as if you had run on flat ground. This is exactly how elite trail runners approach course recces.
Hill repeats: GAP as intensity reference
Hill repeat sessions are highly effective for building power and VO2max. But how do you know if your effort is sufficient when the gradient and speed change with every rep?
Use GAP as your target intensity reference. For example: if your 5km pace is 4:30/km, aim for a GAP between 4:10 and 4:20/km on each hill rep. That range approximates VO2max intensity, regardless of the hill’s gradient.
Practical benefit: you can compare reps on different hills, or track progress from session to session without changing your circuit. GAP standardises the effort. That is the modern training tool at its best.
GAP limitations: what it does not measure
GAP is powerful. But it is not magic. Understanding its limits prevents misinterpretation.
Terrain technicality
This is the primary limitation, officially acknowledged by Strava. GAP models the energy cost of the slope, not the surface. Running on a rocky trail at 8% gradient is not equivalent to running on tarmac at 8% gradient — same GAP, very different actual effort.
On highly technical terrain (boulders, roots, snow, scree), your real effort will consistently exceed what GAP indicates. Factor in a mental “technicality penalty” on those sections — or cross-reference GAP with heart rate for a more complete picture.
Weather and equipment
Headwind, heat, mud, fresh snow: GAP sees none of it. A trail run in heavy rain with 400m of elevation on a muddy path will cost far more than the same run in dry conditions — for the same displayed GAP.
Same applies to footwear: spiked shoes on soft terrain or snow add a biomechanical cost the algorithm ignores. GAP is a comparison tool, not an absolute measure of total physiological effort.
GPS accuracy
GAP is calculated from GPS and altimetric data. A poorly accurate GPS signal (dense forest cover, for example) produces erroneous slope data, and therefore a distorted GAP — sometimes spectacularly so. If your GAP shows absurd values after a run in deep forest, check the GPS quality of your recording before questioning your fitness level.
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FAQ — Average GAP in Running
What is average GAP on Strava?
Average GAP (Grade Adjusted Pace) is the mean of your equivalent flat-ground pace, calculated across your entire activity accounting for elevation. It allows you to compare efforts across runs on different types of terrain — flat, hilly or mountainous.
Why is my GAP faster than my actual pace?
Because you ran on terrain with positive elevation (climbs). Uphill, your physical effort is greater than on flat ground at the same speed. GAP “translates” that effort into a flat equivalent — which is why the value is faster than your GPS speed.
What is the difference between GAP and average pace on Strava?
Average pace is the arithmetic mean of your speed across the run (distance divided by time). GAP is the mean of your grade-adjusted paces, recalculated metre by metre. On flat terrain they are identical; on hilly terrain they can diverge by 30-60 seconds per kilometre or more.
Can I display GAP in real time on a GPS watch?
Yes, on certain models. Garmin watches (Forerunner 955, Fenix, Epix) natively display GAP as a data field in real time. COROS watches and Apple Watch (via the Strava or Runalyze app) also offer this feature. Particularly useful for trail runners managing effort by actual exertion rather than displayed speed.
Is GAP reliable on technical trail terrain?
Partially. GAP is reliable for the gradient component, but it does not account for terrain technicality (rocks, roots, mud) or weather. On very technical trails, your real effort will exceed what GAP indicates. Always cross-reference GAP with heart rate for a complete picture on technical terrain.
How can I improve my average GAP?
Improving your GAP means improving your overall running performance: building aerobic endurance, doing interval training, strengthening quads and glutes for climbing, and refining your downhill technique. Hill repeat sessions are particularly effective as they improve both muscular power and VO2max — the two factors that drive GAP improvement most quickly.
Conclusion
Average GAP is not a tech gimmick. It is one of the most reliable effort metrics available, particularly valuable on varied terrain. Its strength: it reflects what you actually produce — instantly, without being skewed by heat, fatigue or the course profile.
Start by simply observing your GAP on your existing runs. Then use it to pace your next long hill session, or to set intensity targets on your hill repeats. The understanding comes through experience, not theory.
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