How accurate is this calculator?

With a power meter, this is the most accurate way to estimate cycling calories. The 24% gross efficiency is well-established for trained cyclists, giving accuracy within 5-10%.

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?

Human muscles convert about 24% of metabolic energy into mechanical work (power). The remaining 76% is lost as heat. So total calories burned is about 4x the mechanical energy.

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

Minutes

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 approximately 0.24 (24%) for cycling, 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 is close to 1).

Frequently Asked Questions

Related Calculators

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Estimate your Functional Threshold Power from test results.

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TSS Calculator

Calculate Training Stress Score from power and duration.

Training Load Calculator

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.