You’re planning your target time, looking at the course profile and asking yourself: how much slower will this actually be with all these climbs? Whether it’s a 10K, a half marathon or a marathon: elevation gain costs more time than the map might lead you to expect. We’ll explain why that is, and how you can roughly estimate what a climb actually costs you.
Why does running uphill cost so much more energy?
On flat terrain you need a relatively constant amount of energy for every meter you cover, regardless of pace. As soon as the course starts to climb, that changes fundamentally: a large part of your energy no longer goes into forward motion, but into lifting work — you have to raise your body weight against gravity. Lab studies show that energy expenditure when running on flat terrain is around 3.4 joules per kilogram and meter, and rises to almost 19 joules per kilogram and meter on a 45% gradient — more than five times as much. Fortunately, most race courses stay in far more moderate ranges of 1 to 6%, but the underlying mechanism stays the same at every distance: every meter of elevation gain costs noticeably more than a meter on the flat.
Does a descent make up for the extra effort?
The intuitive hope of many runners: what you lose uphill, you get back on the descent. Unfortunately that’s only partly true. Muscle efficiency differs going uphill and downhill: above a gradient of around 15%, efficiency approaches that of a concentric muscle contraction; below a downhill gradient of around 15%, it approaches that of an eccentric contraction, which works far less efficiently. In practical terms this means: the energy you gain from a descent is structurally smaller than the energy you lose on an equally steep climb. That’s why even a course with a net elevation difference of zero — say an out-and-back over the same hill — costs more energy overall than the same distance on the flat.
On moderate descents (up to around 10%) you get back roughly 30 seconds per 100 meters of elevation lost — about half of what the same climb cost you. Once the descent gets steeper than around 15%, the effect even reverses: the braking effort your leg muscles have to produce to keep you from being carried downhill uncontrollably then costs more energy than gravity gives you. This also explains why steep, long downhill stretches damage the leg muscles especially heavily — particularly over long distances, it only becomes noticeable as the strain continues.
How much time do 100 meters of elevation gain actually cost?
As a rule of thumb for constant effort (not constant pace): 100 meters of additional climbing cost around one minute, extrapolated to the respective race distance. In a 10K this is proportionally more noticeable than in a marathon, because the same time difference is spread over a shorter total time. For context: research on elevation profile and altitude among elite marathon runners shows that hilly courses slow performance by somewhere in the range of 1 to 5% compared to a similar flat course. Applied to a four-hour marathon, that corresponds to roughly 2.5 to 12 minutes, depending on how steep the climbs are and how they’re distributed.
Important: these figures apply to constant physiological effort. If you stubbornly try to hold your planned per-kilometer pace, you’ll burn considerably more energy on the climbs than the pure time difference suggests — and you often pay for it only toward the end of the run.
A real-world example: the 2026 European Championships marathon in Birmingham
How this plays out in reality was shown by the marathon at the 2026 European Athletics Championships in Birmingham. The course featured eight laps of 5 kilometers through the city center, with around 700 meters of elevation gain and numerous technical 90-degree corners. A loop course with start and finish in the same place means: on net, the course is elevation-neutral — you go up about as much as you come down.
The winner, Amanal Petros, with a personal best of 2:04:03 (Valencia 2025), won in 2:09:11 — a good five minutes slower than his best mark. Matthias Kyburz, whose personal best stands at 2:06:48 (Seville 2025), finished 17th in 2:11:42, just under five minutes above his PB.
Does that match our rule of thumb? With 700 meters of climbing and roughly the same amount of descent, the calculation of climbing and descent costs (around 60 seconds lost per 100 meters uphill, around 30 seconds gained per 100 meters downhill) yields a purely elevation-related extra effort of roughly three and a half minutes. The actual gap to their PB was somewhat larger for both athletes, which is plausible: the many technical corners cost additional pace, and a championship race is run tactically rather than in the pace mode of a PB hunt. So the elevation profile alone explains a large part of the difference — but not all of it.
Why world records only count on (almost) flat courses
The world governing body World Athletics is also well aware that elevation gain — and above all net descent — massively influences finish times. For a road-running world record to be recognized, the elevation difference between start and finish must not exceed a ratio of 1:1000, i.e. one meter per kilometer, and that applies regardless of the distance. This is why even prestigious races like the Boston Marathon are not recognized as world-record courses, due to their point-to-point layout and excessive net descent — even though outstanding times are regularly run there.
What does this mean for your race tactics?
- Pace by effort, not by the clock: Deliberately slow your tempo on the climbs and let yourself run a bit faster again on the descents, instead of desperately clinging to a constant pace.
- Plan for the elevation in advance: Before the race, take a look at the course profile and think roughly about which kilometers you’ll “lose” time on and where you can make it up again. Our race time calculator is there to help you
- Don’t underestimate steep downhill sections: Long, steep descents don’t spare your legs — they tire the muscles even more, even on shorter distances.
- Set a realistic target time: On a hilly course, your best time from a flat course isn’t a realistic goal, even if your fitness is just as good.
Conclusion
Elevation gain is no minor detail: it noticeably affects your target time — whether 10K, half marathon or marathon — and can be roughly estimated at around one minute per 100 meters of climbing. A descent only partly makes up for this extra effort, which is why even elevation-neutral courses are more demanding than purely flat ones. If you factor this into your pacing, you’ll reach the finish more relaxed and faster in the end.
By the way: our race time calculator automatically factors your race’s course profile into its target-time prediction, so you don’t have to work out for yourself how many seconds the next climb will cost you.