Understanding BMR and Daily Calories (TDEE)

Last updated: 2026-06-25

What is BMR?

Basal metabolic rate (BMR) is the minimum energy your body uses to keep you alive at complete rest — heartbeat, breathing, body temperature, brain activity and cell renewal. Strikingly, BMR makes up about 60–70% of the total calories you burn each day. In other words, most of the energy we use goes not to exercise but to simply being alive.

BMR depends on weight, height, age and sex. Generally it's higher with more weight and height, at a younger age, and in men. People with more muscle have a higher BMR at the same weight, because muscle burns more energy at rest than fat.

What is TDEE?

TDEE (Total Daily Energy Expenditure) is the sum of all the energy you actually burn in a day, on top of BMR. It usually has four components.

• Basal metabolic rate (BMR): about 60–70% of the total.
• Activity energy: energy used in exercise and daily movement (about 15–30%).
• Thermic effect of food (TEF): energy used to digest and absorb food (about 10%).
• Non-exercise activity (NEAT): posture, fidgeting and other unconscious movement.

TDEE = BMR × activity factor
The activity factor bundles activity energy and the thermic effect of food into one convenient multiplier.

The BMR formula: Mifflin-St Jeor

There are several formulas for estimating BMR, but the Mifflin-St Jeor formula, published in 1990, is regarded as one of the most accurate for modern eating habits. It's known to have less error than the older Harris-Benedict equation.

For example, a 30-year-old man at 175 cm and 70 kg: BMR = (10×70) + (6.25×175) − (5×30) + 5 = 700 + 1093.75 − 150 + 5 ≈ 1,649 kcal. If doing this by hand is tedious, just enter your values in the Calorie Calculator to get BMR and TDEE at once.

Activity factor: which one fits you?

To get TDEE you multiply BMR by an activity factor based on your usual exercise and work intensity, as below. Being honest about your real weekly activity is key to an accurate result.

Many people overestimate their activity level. If you hit the gym 3 times a week but sit the rest of the time, you may be closer to "light" than "moderate."

Applying it to weight management

Weight comes down to the balance between energy in and energy out. TDEE is the baseline that tells you where that balance sits.

Losing about 1 kg of fat takes roughly a 7,700 kcal deficit. Cutting 500 kcal a day gives about a 3,500 kcal weekly deficit — around 0.45 kg loss in theory. Rather than slashing more than 1,000 kcal a day, keeping a steady, moderate deficit better preserves muscle and prevents rebound.

Cautions and limits

• It's an estimate: being formula-based, it can be off by roughly ±10% depending on muscle mass, hormones, genetics and gut environment.
• Metabolic adaptation: eating little for a long time can make your body conserve energy, lowering your TDEE.
• Verify in practice: the most accurate approach is to keep the diet for 2–3 weeks, watch your weight change, and adjust intake.
• Don't go below BMR: consistently eating under your BMR risks muscle loss and nutrient deficiency.

Action steps in brief

1. Enter sex, age, height, weight and activity in the Calorie Calculator to get BMR and TDEE.
2. Set your intake based on your goal (maintain, lose or gain).
3. Check your target weight range with the BMI Calculator and Ideal Weight Calculator.
4. Track weight every 2–3 weeks and fine-tune intake.

This article is for general health information and does not replace diagnosis or treatment. Discuss your individual nutrition and exercise plan with a professional.

Last updated: 2026-06-25