Ultra Endurance Nutrition Calculator

Calorie and electrolyte plan for events over 12 hours.

Inputs

Body weight (kg)

Event duration (hrs)

Intensity

Temperature (°C)

Altitude (m)

Tab to move between fields

Results

Total calories needed

10,710

Carbs/hour (g)70

Total carbs (g)1,260

Fat fuel (g)630

Fluid/hour (mL)650

Total fluid (L)11.7

Sodium/hour (mg)540

Total sodium (mg)9,720

Caffeine/dose (mg)56

Calories/feeding249

How to Use This Calculator

Enter Body weight (kg), Event duration (hrs), and Intensity.
Set Easy / hiking pace, Light endurance, and Steady endurance.
Adjust Hard tempo, Race pace as needed.
Review the Total calories needed result.
Use Carbs/hour (g) and Total carbs (g) to inform your decision.

How the result changes with Body weight (kg)

Body weight (kg)	Total calories needed
47	7,191
90	13,770
141	21,573
183	27,999

What each input means

Body weight (kg): Your body weight in kilograms.
Event duration (hrs): Expected event duration in hours.
Intensity: Event intensity level.
Temperature (°C): Expected ambient temperature in Celsius.
Altitude (m): Average event altitude in meters above sea level.

What each result means

Total calories needed: Total estimated caloric expenditure for the event.
Carbs/hour (g): Target carbohydrate intake per hour.
Total carbs (g): Total carbohydrates needed for the event.
Fat fuel (g): Estimated fat grams burned beyond carb intake.
Fluid/hour (mL): Target fluid intake per hour adjusted for heat and intensity.
Total fluid (L): Total fluid requirement for the event.
Sodium/hour (mg): Sodium replacement target per hour.
Total sodium (mg): Total sodium needed across the event.
Caffeine/dose (mg): Recommended caffeine per dose (every ~4 hours).
Calories/feeding: Target calories per feeding interval (~25 min).

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Body weight (kg) = 70, Event duration (hrs) = 18, Intensity = 3, Temperature (°C) = 25 = 5 input(s) provided
Calculate Total calories needed
Total calories needed = totalCalories * altitudeMultiplier
10710 = 10710
Calculate Carbs/hour
Carbs/hour = 40 + intensityLevel * 10
70 = 70
Calculate Total carbs
Total carbs = carbsPerHr * eventDurationHrs
1260 = 1260

Engine last updated August 5, 2026.

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