What is the difference between BMR and TDEE?

BMR (basal metabolic rate) is the energy you burn at complete rest. TDEE (total daily energy expenditure) is BMR multiplied by an activity factor — the total calories you burn in a normal day, including movement and exercise. You eat relative to TDEE, not BMR.

Should I use BMI or TDEE for weight loss?

Use TDEE to set your calories: eat below it to lose fat. BMI is only a rough screening tool for health risk by height and weight; it does not tell you how many calories to eat and can mislabel muscular people as overweight.

Which number matters most for fat loss?

TDEE. Fat loss happens when your intake is below your TDEE. BMR is the floor you should not eat under for long; BMI is just a health-risk reference.

Nutrition

BMR vs TDEE vs BMI: Which Number Should You Use?

Q: How do I calculate TDEE?

Estimate BMR with the Mifflin-St Jeor equation, then multiply by an activity factor from 1.2 (sedentary) to 1.725 (very active). A free TDEE/calorie calculator does this instantly.

📅 3 June 2026⏱ 7 min read

TL;DR

BMR = calories at rest (your floor)
TDEE = BMR × activity = calories you burn per day (use this to set your diet)
BMI = a rough height/weight health screen (not a calorie tool)
For fat loss or muscle gain, TDEE is the number that matters.

1) Three numbers, three jobs

People mix these up constantly, then wonder why their diet isn’t working. Here’s the one-line version of each:

Number	What it is	Use it for
BMR	Energy burned at complete rest (breathing, organs)	Knowing your safe calorie floor
TDEE	BMR × activity factor = total daily burn	Setting calories for fat loss / gain
BMI	Weight ÷ height² — a health-risk screen	A rough check, nothing more

2) BMR — your baseline

The Mifflin-St Jeor equation is the modern standard:

Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Don’t eat below your BMR for long stretches — it tanks energy, sleep and adherence, and costs muscle.

3) TDEE — the number that runs your diet

Multiply BMR by how active you are:

Activity	Multiplier
Sedentary	1.2
Lightly active	1.375
Moderately active	1.55
Very active	1.725

Eat at TDEE → weight stable. Below → fat loss. Above → weight gain. This is the only number you adjust to change your body.

4) BMI — useful, but overrated

BMI sorts people into “underweight / normal / overweight / obese” by height and weight. It’s a quick population-level screen, but it can’t see body composition — a muscular athlete and an unfit person can share a BMI. Use it as a loose reference, not a calorie plan.

5) Calculate yours now (free)

BMR CalculatorYour resting calorie burn TDEE / Calorie CalculatorDaily calories by goal BMI CalculatorQuick health screen

The catch: these numbers are estimates. Your real maintenance can be ±15% off the formula. That’s why KeplerFit tracks your actual weight trend over 2–4 weeks and recalibrates your true TDEE from your data — so your targets stop being a guess. See it in the app →

6) Which one should you use?

Want to lose fat or gain muscle? → TDEE (eat below or above it).
Worried you’re eating too little? → check you’re above BMR.
Just want a health snapshot? → BMI, then move on.

FAQ

What’s the difference between BMR and TDEE?

BMR is rest-only burn; TDEE is BMR × activity = your full daily burn. Diet is set against TDEE.

BMI or TDEE for weight loss?

TDEE. BMI doesn’t tell you how many calories to eat.

How do I calculate TDEE?

BMR (Mifflin-St Jeor) × activity factor (1.2–1.725). The free calculator above does it instantly.