In-Workout Carb Calculator
Pick your session, get your carb-per-hour target, scaled to your bodyweight. Fuel for the work, not just the clock.
hr
min
Enter your weight, duration, and session type to see your target.
Coach's note
More is almost always better. When you're stuck between numbers, round up. I average ~150 g/hr racing and on long prep sessions, but that took months to tolerate. Your gut is trainable: practice your fueling in training (GI training) and build the numbers up gradually before you push them in a race.
Fueling guidelines & caveats
Guideline 1
Easy training under 1 hour (Z1-Z2)
No mid-exercise carbs required. A gel is reasonable if you feel depleted or want to support recovery ahead of a heavy training day.
Guideline 2
Easy training 1-2 hours (Z1-Z2)
Aim for 45-60 g/hr (reference athlete). Supports recovery and adaptation without negatively impacting fat oxidation.
Caveat: Female athletes should not underfuel. Low energy availability can disrupt the endocrine system and lead to long-term health and performance issues.
Caveat 2: Athletes with a history of eating disorders or related health issues should aim for at least 60-90 g/hr on all sessions over 1 hour, regardless of intensity. Accidental underfueling carries a much higher cost in this population.
Guideline 3
Easy training over 2 hours (Z1-Z2)
Aim for 60-75 g/hr (reference athlete). Many can "get through" these with less, but the recovery cost is rarely worth it. As duration climbs, so does the demand on recovery and adaptation.
Guideline 4
Easy-moderate sessions that aren't purely easy
Longer rides, long runs, many marathon workouts. Aim for 75-90 g/hr (reference athlete), regardless of duration. Most long runs aren't truly easy. Higher intake improves performance, supports adaptation, and gives valuable gut training.
Guideline 5
Hard workouts under 90 min (Z3+)
Aim for ~60 g/hr (reference athlete). Covers most mid-week workouts where the goal is adaptation, not just survival. No fat-oxidation benefit to underfueling short, hard sessions.
Guideline 6
Hard workouts over 90 min (Z3+)
Aim for 75-90 g/hr (reference athlete).
Guideline 7
Advanced fueling experimentation
Once comfortable at the standard high-carb range, experiment with 105-120+ g/hr (reference athlete) on hard sessions over 90 min or easy/moderate sessions over 2 hours. Going higher tends to favor faster athletes with higher outputs, but the standard range works for almost everyone and is what most people mean by "high-carb fueling."
Guideline 8
Racing
Apply Guidelines 6 & 7 based on effort and duration. GI issues in races usually come from pushing high carb without practice, or holding high intake when effort drops (long downhills, late-race fatigue). Fuel for effort, not just time.
Caveat: GI issues can also come from doing extreme or unfamiliar things during the carb-load period. Don't overdo your diet race week. Reduced training volume already boosts glycogen storage if you're eating normal, satisfying meals.
How the targets are calculated: the ranges above are written for a reference ~70 kg athlete. The calculator anchors them to your 1 g/kg/hr rule and scales each band to your actual bodyweight, so the recommendation tracks your size instead of a fixed gram number.