Trail effort distance
Twenty kilometres on trail is not twenty kilometres on road. Enter the distance and the climb, and we show the flat equivalent and a rough time.
The list filters as you type
For example 5:30
Effort distance
45.0 km
The course tires you like this many flat kilometres. · ITRA category: S · Estimated time: 5:30:00
The effort distance uses the rule of thumb trail runners rely on: every 100 m of climbing counts as one flat kilometre. The time estimate follows Naismith’s rule: one hour is added to the flat time for every 600 m of ascent. Technical ground and long descents make it slower.
These are general ranges and assume normal conditions. Trail, heat, elevation gain, wind and technical ground all make the real time longer.
Frequently asked questions
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Does this hold for ultra distances?
It gives a rough frame, but in long ultras night, sleep, fuelling and aid station stops decide the total. Use it alongside your own pacing data.
Why is descent not counted?
Short descents make you faster, long technical ones slow you down, and on most courses the two cancel out. On very steep descents leave extra margin.
How many kilometres is 100 metres of climbing worth?
The common rule is that every 100 metres of elevation gain costs about the same as one flat kilometre. A 20 km course with 1,000 metres of climbing therefore feels like 30 km on the flat.
Why is my average pace so slow on trails?
Technical ground, hiking the climbs and braking on the descents change the whole picture. On a course with 50 metres of climbing per kilometre, pace runs 1-3 minutes per kilometre slower than road running at the same effort. That is expected, not lost fitness.
What is Naismith's rule?
Proposed by the Scottish mountaineer William Naismith in 1892: add one hour to the flat walking time for every 600 metres of ascent. Running is faster, but the relative cost of climbing is similar, so the rule still gives a usable rough estimate.
What is km-effort, and is it the same as effort distance?
It is the same calculation. ITRA (International Trail Running Association) compares courses in km-effort, defined as distance in km plus ascent in metres divided by 100. A 45 km course with 2,500 m of climbing is 70 km-effort. The effort distance on this page uses that formula.
What do the ITRA categories (XXS-XXL) mean?
ITRA sorts races into seven sizes by km-effort: XXS below 25, XS 25-44, S 45-74, M 75-114, L 115-154, XL 155-209 and XXL 210 or more. The category describes scale rather than difficulty; technical ground and climate can make two races in the same category feel very different.
Is an ITRA point the same as an ITRA category?
No. The category (XXS-XXL) describes the size of the course and comes from distance and ascent. ITRA points (1-6) are a performance score awarded to finishers and are what races like UTMB ask for at entry. Our race pages list the two in separate columns.
How much climbing per kilometre counts as a lot?
A rough scale: 10-20 m per kilometre is rolling, 20-40 m typical trail, 40-60 m hard and above 60 m mountain running. 1,500 m over 30 kilometres is 50 m per kilometre and will mean hiking sections for most runners.
What do poles gain you on trails?
On steep climbs they spread the load to your arms and delay leg fatigue; studies report 5-10% energy savings on long ascents. On flat or technical descents they can slow you down. Practise with them before racing, since most races require you to carry them from start to finish.
How much of a trail race will I spend walking?
On courses with more than 40 m of climbing per kilometre, most amateurs walk 20-40% of the total time, and more in ultras. Fast hiking is a tactic rather than a failure: on a steep ramp it gives nearly the same speed for far less energy.