What is a Marathon Fueling Calculator?

A tool that estimates your hydration and carbohydrate needs per hour during a marathon based on weight, pace, temperature, and sweat rate.

How accurate is the calculator?

It's based on peer-reviewed sports nutrition guidelines. We recommend testing your plan in long runs to fine-tune it.

How do I use the Marathon Fueling Calculator?

Enter your body weight, goal marathon time, expected race temperature, sweat rate, GI sensitivity, and caffeine usage. The calculator will generate hourly carb, fluid, and sodium recommendations.

When should I start fueling during a marathon?

Begin consuming carbohydrates after 45-60 minutes of running. Start hydrating 2-3 hours before the race and maintain regular intake throughout.

Marathon Fueling Calculator

Get your personalized hydration and fueling strategy for optimal marathon performance

Tailored recommendations based on your race conditions and body composition

Marathon Fueling Calculator

Our calculator uses your weight, goal time, sweat rate and GI tolerance to generate a tailored carb-and-fluid plan for race day.

Enter your details below to receive a personalized nutrition and hydration strategy based on sports research.

Body Weight (lbs)

Expected Marathon Time

Expected Race Conditions

Your Sweat Rate (if known)

GI Tolerance Level

Caffeine Usage

🧪 Science-Based

Our recommendations are based on the latest sports nutrition research from the International Olympic Committee and International Society of Sports Nutrition.

🎯 Personalized

Calculations account for your body weight, race conditions, sweat rate, and individual tolerance factors for optimal performance.

⏰ Timeline-Based

Get specific guidance on what to consume and when, from 3 days before your race through the finish line.

💡 Pro Tips

Practice your fueling strategy during long training runs
Never try anything new on race day
Adjust timing based on your personal tolerance
Consider weather conditions for hydration needs
Considering supplements? Read our guide to sodium bicarbonate and GI risk before race day

Marathon Fueling Calculator

Marathon Fueling Calculator

Your Personalized Race Day Nutrition Plan

🧪 Science-Based

🎯 Personalized

⏰ Timeline-Based

💡 Pro Tips