RACE PLANNER
Aid station splits, drop bags, crew logistics, and pacers. Free to use. Upload your Garmin data to get splits built on your actual VO₂ max, heart rate zones, and training load. Show up race ready.
Plan My RaceHow it works
From race entry to a shareable crew plan in four steps.
Pick from 5 pre-loaded races: Western States, Leadville, Bighorn, Kettle Moraine, and Javelina. Each comes with GPS-verified elevation, official cutoffs, and crew access flags already set. Running something else? Upload the course GPX or enter stations by hand.
Enter your start time. Historical weather for your race date and location is pulled automatically and pre-sets a heat adjustment. Review altitude and night running penalties, adjust any slider before you calculate.
The planner outputs predicted arrival times, cutoff buffers, confidence bands, and crew arrival windows across every station. Upload your Garmin data for splits built on your actual VO₂ max and training load, or use your own pace estimate for free.
Copy one link and send it. Your crew sees arrival windows, task lists, and one-tap directions to each stop. No account needed on their end. Print it if they prefer paper.
Free to use. Upgrade for personalized splits.
The full race planner is free. Every tab (Aid Station Timing, Drop Bags, Crew Logistics, and Pacers) is available without an account. Upload your Garmin data to unlock predictions calibrated to your actual fitness and personalized recommendations on every tab.
- ✓ Aid station timing (enter your own pace)
- ✓ Drop Bags tab (add items manually)
- ✓ Crew Logistics tab
- ✓ Pacers tab
- ✓ Excel export
- ✓ Everything in Free
- ✓ Splits calibrated to your VO₂ max, heart rate zones, and training load
- ✓ Personalized drop bag recommendations based on your race data
- ✓ Personalized crew task suggestions based on your race data
How the predictions are calculated
The timing model combines your fitness data with course variables and race-day conditions. Here is what drives each part of the prediction and where the numbers come from.
Your easy pace is derived from your VO₂ max using the Jack Daniels VDOT framework (Daniels & Gilbert, 1979). The model targets approximately 65% of VO₂ max effort, the intensity most ultramarathon runners sustain on the early miles of a 100-mile race. Without Garmin data, you can enter your own pace estimate.
Each segment adds a climb penalty based on your average elevation gain per training run. Runners who train with more vert receive a smaller penalty. The penalty coefficient ranges from 0.75 min per 1,000 ft (mountain runners) to 1.8 min per 1,000 ft (flat-terrain runners). These values are calibrated to observed finishing times across race splits data.
Pace degrades non-linearly after mile 25 and accelerates for runners with elevated Zone 3 training. Zone 3 (grey zone) training builds less aerobic base than true Zone 2 work, which is associated with more pronounced late-race slowdown. The secondary collapse rate after mile 40 reflects glycogen depletion and GI stress compounding in grey-zone dominant athletes.
The heat multiplier is adapted from research on temperature's effect on endurance performance (Ely et al., 2007, International Journal of Sports Medicine). The original study focused on marathon runners; we apply a modified curve for ultramarathon durations, where heat exposure is prolonged but intensity is lower. The historical average high temperature for the race date and location is fetched automatically from the Open-Meteo archive (ERA5 reanalysis data) and pre-sets the slider. You can adjust it before calculating.
Note: the specific penalty curve for ultramarathon durations is a calibrated estimate, not a direct lift from the literature. We are transparent about this distinction.
The altitude multiplier reflects the reduction in aerobic capacity at elevation for non-acclimated runners. Below 5,000 ft there is no meaningful effect. Above 5,000 ft, the penalty is approximately 1% per 1,000 ft; above 8,000 ft it steepens to approximately 2.5% per 1,000 ft. These values draw on altitude physiology research including Fulco et al. (1998) and the well-established relationship between altitude and VO₂ max decline.
Note: ultramarathon runners operate well below VO₂ max, so the effective pace impact of altitude is smaller than it would be in a road marathon. The penalty represents a conservative estimate for non-acclimated runners.
A 10% pace penalty is applied to miles run between sunset and sunrise, with a 1-hour twilight ramp on each end. Race split analyses from multi-day ultras including UTMB show runners slowing 8–15% during night hours relative to equivalent daytime segments. Sunrise and sunset times are calculated astronomically from the race date and location (Spencer 1971 formula), accurate to within approximately 15 minutes for latitudes between 25°N and 60°N.
Note: the 10% figure is a midpoint estimate. Actual impact varies with headlamp quality, terrain technicality, and individual night-running experience. The toggle lets you disable this adjustment if you run well at night.