Cycling Calorie Burn by Power Calculator
kcal ≈ avg watts × hours × 3.6 — direct from work done (kJ ≈ kcal at 25% gross efficiency).
Result
Calorie burn
1,434 kcal
Work = 1,440 kJ; quick rule: kJ ≈ kcal.
- Average power200 W
- Duration120 min
- Work1,440 kJ
- Efficiency24%
- Calories burned1,434 kcal
- Quick formula1,440 kcal (kJ ≈ kcal)
Step-by-step
- Work in kJ = 200 W × 7,200 s / 1000 = 1,440 kJ.
- kcal = kJ / 4.184 / efficiency = 1,440 / 4.184 / 0.24 = 1,434 kcal.
- Note: at 24% efficiency the units cancel so kJ ≈ kcal.
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
Garmin uses heart-rate-based estimates without a power meter — typically over-estimates 20-50%. With a power meter, Garmin and this calc agree.
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