Racing · Free tool
Ultramarathon Split & Cutoff Planner
An even pace means nothing on a mountain course. Copy each checkpoint’s distance and climb from your race guide and set a goal time. The planner divides that time by how hard each section really is, with time at aid stations and a late-race slowdown built in. Add the cutoffs to see your margin at each one.
Km-effort: counting the climb
The planner measures each section in km-effort: its distance in kilometres plus one for every 100 m of climbing. A 50 km race with 2,800 m of climbing is 78 km-effort, so it runs more like a flat 78 km than a flat 50. ITRA uses the same measure to put trail races into categories.
Your goal time is shared out by km-effort, so a short, steep section gets as much time as a longer, flatter one of the same effort. Descents are not counted: on smooth trail they give a little time back, on technical ground they cost some, and across a whole race the two roughly cancel.
Slowdown and aid stations
Almost nobody runs an ultra at an even effort. The slowdown setting makes each section progressively slower for the same km-effort: with “Typical” you finish about 10% slower than you started, while the sections still add up exactly to your goal time. Use “Even” for a short trail race and “Big” for a first 100-miler.
Aid-station time adds up quickly. Three minutes at eight stations is 24 minutes of your goal time spent standing still, so the planner takes it out before sharing out the moving time. Longer races usually justify longer stops, especially where you have a drop bag.
Planning around cutoffs
Early cutoffs are often the tightest, because they are set to protect the rest of the course. If a margin in your plan is under 30 minutes, treat it as a warning: a queue on the first climb or one slow aid station can use it up.
The answer is rarely to go out faster. Shorter stops, quick exits from crowded aid stations and steady early sections usually buy more margin than racing the first climb. Save the table to your phone and check your arrival times against it as you go.
Frequently asked questions
How do I estimate my ultramarathon finish time?
Work out the course’s km-effort and compare it with a race you have finished. If 60 km-effort took you 8 hours, a 78 km-effort race will take at least 10 hours 24 minutes at the same effort pace, and realistically more, because longer races are run slower.
What is km-effort?
Km-effort is ITRA’s measure of how hard a trail race is: the distance in kilometres plus the total climb in metres divided by 100. A 30 km race with 1,500 m of climbing is 45 km-effort.
How long should I spend at aid stations?
In races up to 50 km, one to three minutes per station is common, and quick refills are enough. In 100 km and 100-mile races, five to ten minutes at the main stations is normal. Plan that time rather than letting it happen, because all of it comes out of your finish time.