Race Day Fuel Planner
Science-backed nutrition planning for your next race. Calculate carbs, hydration, and electrolytes based on duration, weather, and your experience level.
Trained guts can handle up to 90g/hr carbs vs 60g/hr for beginners.
Carbohydrates
60g/hr
210g total
Fluids
500-700ml/hr
2100ml (71oz) total
Sodium
500-700mg/hr
2100mg total
Practice Makes Perfect
Always practice your fueling strategy during training runs. Never try new nutrition on race day. Start with smaller amounts and gradually increase as your gut adapts.
Carbohydrate intake recommendations are based on current sports nutrition research, with rates adjusted for effort duration and intensity.
Gut training is crucial—the GI system can be trained to absorb more carbs with regular practice, increasing from ~60g/hr to up to 90g/hr.
Carb Rate Guidelines:
- • <60 min: Water sufficient, minimal fueling
- • 60-90 min: 30-45g/hr
- • 90-150 min: 45-60g/hr
- • >150 min: 60-90g/hr
Share this tool with your training group or embed it on your coaching website.
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How to use this fuel planner
- Race Day mode: Enter your expected race duration, conditions, and fuel preferences to get a personalized fueling timeline.
- Training Week mode: Enter days until your race and body weight to get carb loading targets.
- Practice your plan: Always test your nutrition strategy during long training runs before race day.
- Adjust based on feel: These are starting points—everyone responds differently to nutrition during exercise.
How to Use This Planner
Enter your expected race duration, intensity level, weather conditions, gut tolerance, and fuel preferences. The planner calculates personalized targets for carbohydrate intake (grams per hour), fluid consumption, and electrolyte needs. It generates a timed fueling schedule showing exactly when and how much to consume during the race. You can also switch to training mode to get a carb-loading plan for the days leading up to your event, with daily carbohydrate targets based on your body weight and days until race day.
The Science Behind Race Nutrition
During endurance exercise, your body burns a mix of fat and carbohydrates. At marathon pace and faster, carbohydrates become the dominant fuel source, but your body can only store about 2,000 calories of glycogen — enough for roughly 90-120 minutes of hard running. After that, you need exogenous carbohydrates to maintain pace. Current sports science recommends 30-60 grams of carbs per hour for events lasting 1-2.5 hours, and up to 60-90 grams per hour for longer events when using a glucose-fructose combination. The planner adjusts these targets based on your intensity, duration, and gut tolerance to find a sustainable intake rate.
Frequently Asked Questions
Related Tools
- Pace Calculator — Estimate your finish time to plan fuel timing
- Difficulty Analyzer — Factor in course difficulty when planning nutrition
- Training Pace Zones — Practice fueling at your race-specific training paces
- Race Time Predictor — Predict your finish time to estimate race duration