Fueling plans that
actually fit your race.
Carb, fluid, and sodium calculators for marathon, ultra, and triathlon races — plus practical guides on carb loading, gels, recovery, and training nutrition. Written by runners, for runners.
Marcus Redd, Head Coach
USATF-certified · 2:54 marathoner · Coaching since 2019
Trained endurance runners should aim for 60-90 g of carbohydrate per hour, 400-800 mL of fluid per hour, and 300-800 mg of sodium per hour during a long race — scaled by body weight, pace, heat, and gut tolerance. Each calculator on this site gives a specific, personalised plan.
Race-day calculators
Put your numbers in. Get a printable plan out. All client-side, no account needed.
Marathon Fueling Calculator
26.2 miles — carbs/h, fluid/h, sodium, and gel cadence by weight, pace, and finish time.
Open calculator →Ultra Fueling Calculator
50K to 100 mi. Solids, gels, protein, fluids, sodium, aid-station cadence.
Open calculator →Triathlon Fueling Calculator
Sprint through Ironman. Per-leg carb, fluid, and sodium plans.
Open calculator →Guides
Practical articles, not content marketing.
Marathon Nutrition Guide 2026
Pre-race week, race-morning breakfast, in-race carb cadence, and what to eat after.
UltraUltra Running Fueling Strategy
50K, 50 mi, 100 mi. Why ultras need a different playbook than the marathon.
TriathlonTriathlon Race Day Fueling
Swim start, bike-leg schedule, run-leg conservative fueling, special-needs bag.
Pre-raceCarb Loading Explained
The modern 2-3 day load at 10-12 g/kg/day. Why the old depletion-load is gone.
TrainingHigh-Mileage Training Nutrition
Fueling 50-90 mpw. Daily carbs, protein, under-fueling warning signs.
FuelingGels vs Real Food
When gels win, when real food wins, and a practical food list.
RecoveryPost-Run Recovery Nutrition
The 30-120 min window, carb:protein ratios, and real-world meals.
AlternativeRunning on Keto at Ultra Distance
Honest look: when it works, when it doesn't, and what the evidence actually shows.
ToolsCalorie Tracking Apps for Runners 2026
Ranked review focused on endurance-specific features, not general tracking.
Common questions
How many carbs per hour should a marathon runner consume?
60-90 g/h for most trained marathoners, using a 2:1 glucose-to-fructose ratio to maximise absorption. Use the Marathon Fueling Calculator for a personalised target.
How is ultra-running nutrition different from marathon nutrition?
Ultras last long enough that the gut can't sustain 90 g/h of sugar, fat metabolism engages, and solid food becomes essential. Plan 150-300 kcal/h mixing gels, real food, and salty options, with protein added after hour four.
How do you actually carb-load for a race?
10-12 g/kg/day for 24-36 hours pre-race, low fibre. Expect 2-4 lb water weight. The old 7-day depletion-load is obsolete.
What should I eat for breakfast before a marathon?
3-4 hours out: 1-2 g/kg low-fibre carbs plus 10-15 g protein. Example: bagel with a little peanut butter + banana. Rehearse this exact breakfast in training.
Can you run a 100-miler on keto?
Yes, with trade-offs. Keto-adapted ultra-runners can cover 100 miles at aerobic pace, but any surge above aerobic threshold suffers. Most elites use a mixed strategy and add carbs back in the last third.
Who writes this site
Marcus Redd, Head Coach
USATF-certified running coach. Marathoner (PR 2:54) and ultra-runner. Writes practical fueling protocols for amateur endurance athletes. Coached ~80 runners to first marathons since 2019.
Sara Klein — 2x Ironman finisher — contributes multisport race-day writing.
Read the full editorial standards →