.jpg)
Find these tools useful? Consider supporting future development via the widget in the bottom right corner!
This isn't just a pace calculator; it's a comprehensive race simulation engine designed for the nuances of ultra and trail running. Its purpose is to transform your goal time into a realistic, actionable strategy that accounts for elevation, terrain, weather, and the most critical factor in long-distance running: fatigue.
This first step is crucial. Instead of guessing, you can set an informed goal based on the expected conditions.
Use the "Add Leg" button to map your race from one aid station to the next. For each leg, define its unique distance, elevation, and your planned stop time in minutes at the end of that leg.
A single leg is rarely uniform. Use the "Add Terrain Type" button to break down the leg's composition. The order you add them in matters. The calculator simulates the leg in the sequence you provide.
Example: A 20km leg that is 50% technical trail followed by 50% road is very different from the reverse. If the technical section comes at hour 15 of your race, your fatigue fade will be high. If you then hit the road, your pace will increase, but it will still be influenced by that high fatigue level. This is why the order is so important for an accurate simulation.
Ensure the percentages for each leg add up to exactly 100%.
Your plan is not based on simple averages. It's the result of a sophisticated simulation that layers multiple evidence-based factors to predict your performance:
| Factor | Description |
|---|---|
| Goal-Seeking Algorithm | The calculator runs dozens of full-race simulations, intelligently adjusting the starting pace until it finds the one precise effort level that allows you to meet your goal time exactly after all challenges are factored in. |
| WBGT Heat Model | Instead of just temperature, the planner calculates the Wet Bulb Globe Temperature (WBGT), a metric used by sports medicine professionals that accounts for heat, humidity, wind, and sun to determine the true heat stress on your body. |
| Elevation Adjustment | Based on established models (similar to Naismith's Rule), it adds a time penalty for every meter of ascent and gives a smaller time bonus for every meter of descent to simulate the real effort of running hills. |
| Fatigue Fade | The key to ultra planning. It progressively slows your potential pace based on the hours you've been running, simulating muscle fatigue and glycogen depletion. |
These percentages represent the time penalty for different surfaces compared to a smooth, runnable trail (0%). The defaults are calibrated estimates based on common coaching practice and analysis of race data. You should adjust them based on your personal strengths or specific knowledge of the course.
| Condition | Default % | Description |
|---|---|---|
| Road | -5% | Paved road is faster than trail. |
| Smooth | 0% | Your baseline. Well-maintained singletrack. |
| Mixed | +10% | Typical trail with some roots and rocks. |
| Technical | +20% | Requires focus. Very rocky or rooty. |
| Sandy/Muddy | +30% | Energy-sapping terrain. |
This simulates the unavoidable slowdown from physiological stress. The calculator uses a progressive degradation model, a well-accepted technique in ultra-endurance planning. The percentage is applied per hour of elapsed race time.
| Profile | Example Fade (Hours 10+) | Description |
|---|---|---|
| Elite Runner | 0.5% - 1.0% | Highly trained to resist late-race breakdown. |
| Experienced (Default) | 1.5% | A realistic fade for a well-trained and well-paced runner. |
| Newer Ultrarunner | 2.0% - 3.0% | Newer runners often slow more dramatically. This provides a safer, more conservative plan. |
The first and most important step in any race plan is an honest assessment of your current fitness and capabilities. This tool is powerful, but its output is only as good as the goals you provide. A plan based on an unrealistic goal is a recipe for a tough day.
Ultrarunning is complex. This tool provides a data-driven plan, not a perfect prediction. Unforeseen things happen on race day: a rolled ankle, a nutrition issue, or simply a bad patch.
The most important ultrarunning skill is the ability to adapt. Use this plan as your guide, but listen to your body and be prepared to adjust on the fly. A smart, flexible runner is a successful finisher.
Disclaimer: This is a planning tool, not a substitute for medical advice or personal experience. Please review your plan critically. If you feel it isn't correct for you, or if you find any bugs in the calculations, please let me know via the contact details on the main UltraHub page.
A professional-grade planning tool with advanced customisation.
Based on the conditions, your ideal goal of will feel more like .
We suggest a goal range of .
| Leg Name | Leg Dist. | Total Dist. | Pace | Leg Time | Arrival | Stop | Departure | Elapsed |
|---|
The calculator performs a complex simulation to find the precise pacing required to meet your goal. It works by layering multiple real-world factors:
| Factor | Description |
|---|