Aid Station Pacing Planner
Enter your race checkpoints and goal finish time. Get estimated arrival times at every aid station, segment paces, and hiking zone warnings.
An aid station planner converts a goal finish time into estimated arrival times at every checkpoint, using the distance and elevation between aid stations. TrailMath's free planner ships with presets for UTMB, CCC, Lavaredo, Templiers, Western States, and Hardrock, plus custom races.
Checkpoints (3)
What is an aid station pacing plan?
An aid station pacing plan converts your goal finish time into estimated arrival times at every checkpoint on your race course. Instead of dividing time equally by distance - which ignores the enormous time cost of climbing - it distributes your total race time in proportion to the effort cost of each segment.
A 10km segment with 800m of elevation gain takes roughly the same effort as 18km flat. Equal time splits fail on mountain courses because they assume all kilometres are equal. This planner uses TrailMath's enhanced km-effort model to give you a plan that matches how your body actually experiences the course.
Why trail runners need checkpoint-level pacing plans
Road marathon pacing is straightforward: run even splits, take gels at the stations, finish in target time. Trail ultras are an entirely different problem.
Elevation changes make distance-based pacing dangerous. Running flat pace up a 25% grade leads to blowup within kilometres. The opening section of UTMB from Chamonix to Les Houches feels easy - then the climb to Col de Voza hits and runners who went out on road-pace effort are already in trouble at 8km of a 171km race.
Crew and drop bag logistics require precision. Your crew needs to know when to drive to Courmayeur, when to expect you at Champex-Lac, and when to be waiting at Vallorcine. A pacing plan with realistic arrival times makes the difference between a well-organised crew and one that's always in the wrong place.
Drop bags must arrive before you. Race organisation collects drop bags hours before the start. Knowing you will reach La Fouly at 3am with a target split of 18 hours tells you exactly what gear you need in that bag for the overnight section ahead.
Power hiking decisions need to be pre-planned. The best trail runners don't run every runnable section - they power hike strategically to save legs for the descents. Knowing in advance which segments should be hiked (the planner flags these) lets you make those decisions before fatigue distorts your judgement.
How to use the Aid Station Planner
- Enter your goal finish time Be realistic - use the Race Time Predictor to estimate a finish time based on your current fitness if unsure.
- Select terrain type Choose from road, easy trail, moderate trail, or technical trail. This adjusts the overall effort scale but not the proportional split between segments.
- Add your checkpoints Enter each aid station with cumulative distance from start, total elevation gain, and total elevation loss to that point. Your race guide or GPX file shows these values.
- Read the arrival times The output table shows estimated arrival time, segment pace, km-effort, and a hiking zone warning if the segment is steep enough that power hiking is faster than running.
- Brief your crew Share arrival times with crew and pacers. Build in 10-15 minutes of buffer at crew-access points to account for aid station tasks.
The science behind km-effort pacing
Most runners build race pacing plans by dividing total distance evenly - which ignores the fact that an uphill kilometre takes far longer than a flat one. This planner uses TrailMath's enhanced km-effort model to distribute your goal time proportionally by effort, not by distance.
The km-effort formula for each segment is: distance_km + gain_m/100 + loss_m/150. This is TrailMath's extension of the standard ITRA gain-only formula, which adds descent cost based on Minetti's finding that steep technical descents carry real metabolic load. A 5km segment with 500m of gain and 200m of loss has an effort of 5 + 5 + 1.3 = 11.3 km-effort - equivalent to running 11.3km flat. Time is allocated proportionally to this effort score.
Why gain and loss have asymmetric costs. Minetti et al. (2002) mapped the metabolic cost of inclined locomotion across gradients from -45% to +45%. The key findings: metabolic cost rises steeply above 15-20% uphill grade, making power hiking more energy-efficient than running on steep climbs. On descents, eccentric muscle loading (quads acting as brakes) creates its own metabolic cost - steep technical descents are far more demanding than the same gradient on a smooth fire road. The gain/100 + loss/150 asymmetry in the formula reflects this - gain is more costly per metre than loss, but loss is not free.
Power hiking threshold is flagged at segments where your computed pace exceeds 12 min/km (19 min/mile). This threshold corresponds to the crossover point where walking biomechanics become more efficient than running on steep uphill terrain. Strategic power hiking on marked segments preserves leg muscle for descents and reduces overall race time compared to running everything.
This km-effort model is the same formula used in TrailMath's training engine for load calculation (following Dan Johnston's asymmetric elevation scoring methodology), ensuring consistency between how your training load is measured and how your race effort is planned.
Minetti AE et al. (2002). Energy cost of walking and running at extreme uphill and downhill slopes. J Appl Physiol. 93(3):1039-46. Minetti AE et al. (1995). Mechanical determinants of gradient walking energetics in man. J Physiol. 481(Pt 1):235-43. ITRA. km-effort formula. International Trail Running Association. itra.run
Common aid station planning mistakes
Pacing the opening flat fast, then suffering on the first climb. UTMB's first 8km to Les Houches are the flattest of the race. Runners who treat this as a warm-up sprint arrive at the first climb already above target heart rate. Your plan should show this segment as conservative - the climbs are coming.
Treating descent as "free" time. Technical downhill is muscular work. After 80km of accumulated fatigue, steep descents at Lavaredo's Monte Piana or UTMB's descent to Courmayeur cause significant quad damage. If you run descents at race-start pace in the second half, you will be walking the flats within hours. Plan descent segments conservatively, especially after the halfway point.
Using the same pace for night segments. Most runners are 15-20% slower at night due to reduced terrain visibility, fatigue accumulation, and lower body temperature. A plan that doesn't account for this will show you arriving at night checkpoints 20-40 minutes later than planned. Add a night multiplier to segments you will cover between midnight and 4am.
Zero buffer time at aid stations. Every aid station stop takes real time: refilling water, eating, changing gear, logging with officials. Budget 5-10 minutes per station minimum. A race with 15 checkpoints where you spend 15 minutes each adds 3.75 hours to your race. Elite runners spend 2-3 minutes. Mid-pack runners typically spend 8-12 minutes, often longer.
Not accounting for crew logistics. Crew need time to drive from one access point to the next. At UTMB, the drive from Saint-Gervais to Courmayeur via the Mont Blanc tunnel takes 45-60 minutes with parking. If your split at Saint-Gervais is 5 hours and your estimated Courmayeur arrival is 13 hours, your crew has 8 hours to make a 1-hour drive - easy. But if you're ahead of plan and arrive at Courmayeur in 11 hours, crew who left Saint-Gervais at hour 9 may not be there.
Aid station strategy at iconic races
UTMB (171km, 10,000m D+). The race has 4 crew-access points: Saint-Gervais (22km), Courmayeur (79km), Champex-Lac (125km), and Vallorcine (149km). For a 30-hour finish, a realistic plan shows: Saint-Gervais ~3:30, Courmayeur ~13:00, Champex-Lac ~21:00, Vallorcine ~26:30. The gap between Courmayeur and Champex-Lac is the longest crew-free section (46km, ~8-10 hours for mid-pack runners) and where most DNFs occur. Plan your drop bag at La Fouly (116km) to cover this section with night gear, food, and fresh batteries.
Lavaredo Ultra Trail (120km, 5,850m D+). More frequent aid stations than UTMB - roughly every 10-15km. The key decision point is Cortina d'Ampezzo (80km), the last major crew-access point. From Cortina to the finish (40km) involves the final two major climbs including Passo Giau (2236m). Runners who arrive at Cortina ahead of schedule often go out too fast on the climb to Rifugio Cinque Torri and pay for it on Passo Giau. Use the planner to set a ceiling on your Cortina arrival time, not just a floor.
Western States 100 (161km, 5,600m D+). One of the hottest 100-milers in the world - temperatures in the canyons regularly exceed 38°C in June. Robinson Flat (55km) is the first major crew point and the last point of easy access before the deep canyons. From Robinson Flat to Michigan Bluff (88km) is the most technically demanding section in full heat. Plan extra time for this segment - it consistently surprises runners who have run well to Robinson Flat.
Frequently asked questions
How long should I spend at each aid station in an ultra?
Budget 5-10 minutes at minor aid stations and 10-20 minutes at major crew-access points. The biggest time losses in ultras come from aid stations, not pace - runners who sit down, change shoes slowly, or linger in the warmth often lose 30-60 minutes across a 100-mile race. Have a written list of tasks for each station: eat, refill, swap gear, go. Crew who know their roles dramatically cut your time.
What is the difference between drop bags and crew access?
Drop bags are pre-packed bags you submit before the race, transported by race organisation to designated checkpoints. You can access them alone, without crew. Crew access means your support team can meet you at the checkpoint - they can pace you out, handle your gear, and make real-time decisions. Not all checkpoints allow both. UTMB has crew access at Saint-Gervais, Courmayeur, Champex-Lac, and Vallorcine - and drop bags at several others. Check your specific race guide well in advance.
What should I put in my drop bags for a 100-mile ultra?
Essentials: nutrition matching your per-segment plan (gels, bars, real food), spare headtorch batteries or a backup torch, weather layers if the forecast changes, blister kit and anti-chafe, and a written note of your goal split times. Optional but often valuable: fresh socks, a change of shoes for different terrain, wet-weather gear, savoury food for the night section. Keep bags organised - a panicked rummage at 2am costs minutes.
How do I pace UTMB aid stations correctly?
The biggest UTMB pacing mistake is running fast out of Chamonix and arriving at Saint-Gervais (22km) ahead of plan. The race is won and lost in the second half. Your plan should show conservative splits through Italy, with realistic hiking time for the Grand Col Ferret. From Champex-Lac (125km) onward, plan for a 15-20% pace drop from your first-half average - fatigue, darkness, and accumulated elevation loss takes a toll on quads. Use this planner with your full checkpoint list and goal time to see where your plan is aggressive.
Should I sit down at aid stations in an ultra marathon?
Only if you have a specific medical reason (blister treatment, changing wet gear) or are in genuine distress. Sitting down signals your body to start the recovery process - it becomes harder to get moving again. For routine aid station stops, stay on your feet, keep moving through the checkpoint, and eat while standing. The exception is major crew points where a 10-minute strategic sit with legs elevated before a hard section can pay dividends.
How does km-effort affect aid station arrival times?
The km-effort model distributes your total goal time in proportion to each segment's effort cost - not its distance. A 10km segment with 800m of climbing has the same effort as roughly 18km flat, so it gets nearly twice as much time. This means your arrival time at a high-gain checkpoint will be later than a naive distance-based split predicts. The planner does this automatically - compare the "naive" time (total time / total distance x segment distance) with the planner output to see how much climbs shift your schedule.
Save your plan, add crew notes, and track progress on race day
TrailMath uses these models to build periodized plans adjusted to your goals and terrain.
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