BMR vs RMR: What's The Difference?
Learn the subtle but important distinction between Basal Metabolic Rate (BMR) and Resting Metabolic Rate (RMR).
The Quick Answer
BMR and RMR are very similar but not identical. Both measure how many calories your body burns at rest.
BMR (Basal Metabolic Rate) is measured under very strict conditions: first thing in the morning, after 8 hours of sleep, in a completely fasted state (12+ hours without food), in a dark, quiet room with controlled temperature.
RMR (Resting Metabolic Rate) is measured under less strict conditions: you can have eaten recently, you don't need to sleep in the lab, and the environment doesn't need to be perfectly controlled.
RMR is typically 10-20% higher than BMR because of the less restrictive measurement conditions. For most people, BMR might be 1,500 calories while RMR is 1,600-1,650 calories.
Why The Difference Matters (Or Doesn't)
For most practical purposes, BMR and RMR are interchangeable. Here's why:
Online calculators (including ours) estimate BMR, but because they can't account for perfect fasting conditions, they're actually estimating something closer to RMR.
The 10-20% difference is usually accounted for when you multiply by activity factors to get TDEE anyway.
Unless you're getting professional metabolic testing done in a lab, don't worry about the distinction. Just use the terms interchangeably and focus on tracking your actual results over time.
Which Number Should You Use?
Use whatever number your calculator gives you (usually called BMR) as your baseline, then multiply by your activity factor to get TDEE.
The exact terminology doesn't matter—what matters is consistency. If you're using our calculator, keep using it. Don't switch between different calculators that might use slightly different formulas or definitions.
Track your results for 2-3 weeks and adjust based on real-world outcomes, not calculator semantics.