Triathlete – Nutrition

How Accurate Are Smartwatch Calorie Burn Calculations?

Smartwatches claim to estimate calories burned, but multiple validation studies show errors ranging from 27% to over 90% across major brands. The inaccuracy stems from reliance on heart‑rate and motion data without accounting for metabolic rate or body‑composition differences. Experts recommend using total‑daily‑energy‑expenditure (TDEE) calculators, power‑meter data, and personal hunger cues as more reliable guides. Ultimately, athletes should prioritize macronutrient timing and overall training load over precise calorie numbers when refueling.