Why Do Calorie Calculators Give Different Results?
Calorie estimates differ because equations, activity multipliers, rounding and personal energy expenditure are not identical.
Different BMR equations
Mifflin-St Jeor and revised Harris-Benedict can produce different starting estimates.
Activity multipliers
Two websites can label activity levels differently, causing larger TDEE differences than the BMR formula.
Individual variation
Daily movement, body composition, sleep, health and food tracking can make real needs differ from a formula.
Practical takeaway
Use a calculator as a starting estimate, track a stable routine over time, and adjust with appropriate professional support when health circumstances require it.
Run your own numbers
Use the related Fynzo calculator with consistent assumptions and compare the full result.
Calculate BMR and TDEEReview note
This guide is educational and should not replace medical, financial, legal or tax guidance. Last reviewed August 1, 2026.