How accurate is this calculator?

With a power meter, this is the most accurate way to estimate cycling calories. The default 24% efficiency follows the industry convention used by TrainingPeaks, TrainerRoad and CTS, where the kilojoules of mechanical work roughly equal the kilocalories burned. Note that laboratory-measured GROSS efficiency for most trained cyclists is nearer 20–23% (Moseley & Jeukendrup found ~19.8%), so your true calorie burn may be a few percent higher than shown — lower the efficiency field toward 0.21 for a more conservative (higher-calorie) estimate.

Why not use heart rate for calories?

Heart rate is affected by temperature, caffeine, stress and fatigue. Power directly measures mechanical work output, making it far more reliable for calorie estimation.

What is metabolic efficiency?

Gross efficiency is the share of total metabolic energy you turn into mechanical work at the pedals. For trained cyclists this is typically about 20–24% (the 24% default is an upper-range convention; 25.8% you may see quoted is DELTA efficiency, a different metric). The remaining energy is lost as heat, so total calories burned is roughly 4 to 5 times the mechanical energy you produce.

Do I burn more calories if I weigh more?

If two riders produce the same power for the same duration, they burn approximately the same calories. However, heavier riders typically need more power to maintain the same speed.

BikeCalcs

Calorie Burn Calculator — Cycling Calories from Power

Estimate calories burned cycling based on power output and duration.

Average Power

From your power meter or smart trainer

Hours

Whole hours of ride time

Minutes

Additional minutes beyond whole hours

How We Calculate This

Calorie Calculation from Power

Mechanical Energy (kJ) = Power (W) x Duration (s) / 1000

Total Calories = Mechanical Energy / Efficiency / 4.184

Where efficiency is the rider's gross efficiency (the default 0.24 follows the cycling-tool convention; measured values for most riders are nearer 0.20–0.23), and 4.184 converts kilojoules to kilocalories.

A useful shortcut: kJ from your power meter roughly equals kcal burned, because 1 / (0.24 × 4.184) = 0.996 ≈ 1. If you set a lower, more realistic efficiency such as 0.21, your calorie total rises by about 14% over the kJ figure.

Frequently Asked Questions

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Track acute and chronic training load over time.

Last updated: 2025-02-20

All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.