Carbohydrate Requirement Calculator

Estimate your energy expenditure, substrate burn, and carbohydrate fueling targets for any run.

Body Weight

70 kg

Run Duration

1h 30m

90 min

Intensity

Energy Expenditure

—

kcal

Total Burn

—

kcal/hr

Burn Rate

Carbohydrate —

Fat —

Recommended Carbohydrate Intake

—

g/hr

Hourly Rate

—

g total

Mid Estimate

—

of carb burn

Replacement

Fueling targets are absorption-limited, not weight-dependent. Your gut can oxidise up to ~60 g/hr from glucose alone, or ~90–120 g/hr using glucose + fructose.

Gel Feeding Schedule

When intake exceeds tolerance

Methodology & Assumptions

Energy expenditure is estimated using MET values for running at each intensity (easy ≈ 8.5, moderate ≈ 10.5, hard ≈ 12.5, race ≈ 14.5 METs) multiplied by body weight. Substrate partitioning ratios are approximate and based on respiratory exchange ratio data at corresponding intensities.

Gel schedule assumes 25g carbohydrate per gel, with the first gel at 20 minutes and subsequent gels evenly spaced to meet the mid-range hourly target. Any shortfall between gel carbs and the total target can be covered by carbohydrate drink mix.

Individual requirements vary with gut training status, heat, altitude, fuel type, and fitness level. These estimates are a starting point — not a prescription.

Man running on a road with spectators in the background

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