BMR and TDEE explained
Your body uses energy all day, even at rest. Two numbers matter:
- BMR (basal metabolic rate): the calories your body burns at complete rest to keep you alive: breathing, circulation, temperature and cell repair. For most adults this is 60–70% of daily energy use.
- TDEE (total daily energy expenditure): your BMR plus everything you do on top: walking, work, sport and digesting food. This is your maintenance calories, the amount at which your weight stays stable.
The Mifflin-St Jeor equation
This calculator uses the Mifflin-St Jeor equation, which research has shown to be the most accurate of the common formulas for healthy adults:
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
TDEE = BMR × activity factor
Pounds and inches are converted to kilograms and centimetres automatically.
| Activity level | Factor |
|---|---|
| Sedentary (desk job, little exercise) | 1.2 |
| Lightly active (exercise 1–3 days a week) | 1.375 |
| Moderately active (3–5 days a week) | 1.55 |
| Very active (6–7 days a week) | 1.725 |
| Extra active (physical job plus training) | 1.9 |
Example (US units): a 35-year-old woman, 150 lb (68.0 kg), 5 ft 7 in (170.2 cm), moderately active. BMR = 680.4 + 1,063.6 − 175 − 161 ≈ 1,408 kcal. TDEE = 1,408 × 1.55 ≈ 2,182 kcal a day.
Example (metric): a 40-year-old man, 85 kg, 180 cm, lightly active. BMR = 850 + 1,125 − 200 + 5 = 1,780 kcal. TDEE = 1,780 × 1.375 ≈ 2,448 kcal.
Calories for weight loss or gain
One pound of body fat holds roughly 3,500 kcal (about 7,700 kcal per kg). A daily deficit of 500 kcal therefore leads to about 1 lb (0.45 kg) of weight loss per week, which is a pace most guidelines consider safe and sustainable. The calculator shows TDEE minus 500 as a guide.
- Don’t go below about 1,200 kcal a day (women) or 1,500 kcal (men) without medical supervision.
- To gain weight or build muscle, a surplus of 250–500 kcal plus strength training is usually advised.
- Your metabolism adapts: as you lose weight, your TDEE drops, so recalculate every few kilos or every 10 lb.
How accurate is this?
Any formula is an estimate. Individual BMR can differ by 10% or more due to muscle mass, genetics and hormones, and people tend to overestimate their activity level. Treat the result as a starting point: track your weight for two to three weeks and adjust your intake by 100–200 kcal if the trend does not match your goal.
Check where you stand with the BMI calculator and convert body weight between kilograms and pounds with the kg to lbs converter.
General information, not medical or dietary advice. Pregnant or breastfeeding women, people with medical conditions and athletes should consult a professional.
Tracking and adjusting
Use the calculator as a starting point, then adjust based on results. Track your weight for two to three weeks, ideally at the same time each morning, and look at the average trend rather than daily changes. If your weight is stable while you eat about the calculated number of calories, that number is your real maintenance level.
Frequently asked questions
How many calories should I eat a day?
It depends on your size, age, sex and activity. Typical maintenance needs are around 1,800–2,400 kcal for women and 2,200–3,000 kcal for men. Use the calculator for a personal estimate.
What is the difference between BMR and TDEE?
BMR is the energy you burn at total rest. TDEE adds the energy for daily activity and exercise. To maintain your weight, eat roughly your TDEE.
How many calories should I cut to lose weight?
A deficit of about 500 kcal per day leads to roughly 1 lb (0.45 kg) of weight loss per week. Larger deficits are harder to maintain and can cost muscle.
Which activity level should I choose?
Be conservative. Most office workers who exercise a few times a week fit “lightly active”. Choose “moderately active” only if you train 3–5 times a week with real effort.
What is the difference between calories and kilojoules?
They are two units of energy. One kilocalorie (kcal, the “calorie” on food labels) equals 4.184 kilojoules (kJ).
Last reviewed: 2026-10-06. Results are estimates for information only.