Cycling Calorie Burn by Power Calculator

kcal ≈ avg watts × hours × 3.6 — direct from work done (kJ ≈ kcal at 25% gross efficiency).

Inputs

Result

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How to use this calculator

  • Read average power from your bike computer.
  • Enter ride duration.
  • Pick gross efficiency (24% is typical).
  • Take the answer at ~85-95% confidence.

About this calculator

Cycling calorie burn from a power meter is the most accurate available. Work done in kilojoules ≈ calories burned (uncoincidence: gross efficiency ≈ 24%, and kJ-to-kcal conversion ≈ 4.184, so they cancel). A 3-hour ride at 200W = 200 × 3 × 3.6 = 2,160 kJ ≈ 2,160 kcal. Heart rate-based estimates often overstate by 30-50%. Quick rule: 1 kJ of work = 1 kcal burned, full stop.

Frequently asked

Why is my Garmin estimate different?+
Garmin uses heart-rate-based estimates without a power meter — typically over-estimates 20-50%. With a power meter, Garmin and this calc agree.
Does coasting count?+
Power-based: no, coasting reads 0W. The calc only counts pedaling time. Heart-rate-based methods do count coasting (incorrectly).
What if I don't have a power meter?+
Estimate avg power: 100W = chatting pace, 150W = endurance, 200W = tempo, 250W+ = threshold. Or use a smart trainer.
Why 24% efficiency?+
Mechanical efficiency of human pedaling. Trained cyclists hit 23-25%. Untrained 19-22%. Elite 25-26%. Doesn't change much in practice.
Can I use this to plan nutrition?+
Yes — for rides over 2 hours, plan to consume 60-80g carbs/hour. A 3-hour 200W ride burns ~2,160 kcal; eat ~700-900 kcal during.

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