Why ultra pacing is different
In a road marathon, even pacing is the gold standard. In an ultramarathon, almost nobody runs even splits: terrain, climbing, darkness, heat and fatigue all push pace down as the race goes on. The runners who finish strongly are usually the ones who planned for the slowdown — starting conservatively and budgeting realistic time for aid stations — rather than trying to bank time early.
How the planner works
1st-half pace = p · 2nd-half pace = p × (1 + slowdown)
solved so that total moving time matches your goal
The table then gives the distance, elapsed time and time of day you should reach each aid station — the numbers crews and pacers want.
Ultra pace chart
Average pace (including stops) for common finish times.
| Race | 6 h | 8 h | 10 h | 12 h | 16 h | 20 h | 24 h | 30 h |
|---|---|---|---|---|---|---|---|---|
| 50 km | 7:12/km | 9:36/km | 12:00/km | 14:24/km | 19:12/km | 24:00/km | — | — |
| 50 miles | 4:28/km | 5:58/km | 7:27/km | 8:57/km | 11:56/km | 14:55/km | 17:54/km | 22:22/km |
| 100 km | — | 4:48/km | 6:00/km | 7:12/km | 9:36/km | 12:00/km | 14:24/km | 18:00/km |
| 100 miles | — | — | — | 4:28/km | 5:58/km | 7:27/km | 8:57/km | 11:11/km |
Pacing and planning tips
Walk the climbs early
Power-hike steep uphills from the start. It saves your legs for the second half, when running is worth more.
Use effort, not pace
On trails, pace varies wildly. Heart rate or perceived effort is a better guide; see grade adjusted pace.
Beware the chair
Sitting at aid stations is where many ultras are lost. Have a checklist, refill, and move on.
Eat early and often
Aim for regular carbohydrate from the first hour; plan it with the race fueling calculator.
Know the cutoffs. Most ultras have intermediate cutoff times at key aid stations. Add them to your plan and aim to arrive with a comfortable margin — especially at night, when pace usually drops.
Estimating your flat-course potential? Start from a recent marathon or half in the race time predictor, then add time for terrain and climbing.
Last reviewed: September 2026 · Health disclaimer