Quick answer
Your daily calorie needs (TDEE) are your BMR times an activity factor. With Mifflin-St Jeor, BMR for men is 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5; for women subtract 161 instead of adding 5. To lose 0.5 kg a week, eat about 550 kcal a day below TDEE. A 30-year-old man, 70 kg, 175 cm, training 3–5 days a week, needs about 2,556 kcal to maintain and about 2,006 to lose weight.
What are BMR and TDEE?
Enter your sex, age, weight, height and activity level to get your resting energy (BMR), maintenance energy (TDEE) and daily calories for losing, maintaining or gaining weight, plus protein, fat and carb grams. Choose between Mifflin-St Jeor and Harris-Benedict, and use kg / cm or lb / inches.
How to calculate your calories
- 1
Choose your sex and enter your age (18–100), weight and height; switch units if you prefer lb and inches.
- 2
Pick the activity level closest to a normal week (not your most active one).
- 3
Choose a goal: lose 0.25 – 0.75 kg a week, maintain or gain.
- 4
Read your BMR, TDEE and target calories; pick a macro split to see grams of protein, fat and carbs.
- 5
Track your weight for 2–3 weeks, then adjust by about 100–200 kcal if you're changing faster or slower than expected.
Activity factors
| Activity level | Description | Factor |
|---|---|---|
| Sedentary | Desk job, no exercise | 1.2 |
| Light | Exercise 1–3 days a week | 1.375 |
| Moderate | Exercise 3–5 days a week | 1.55 |
| Active | Exercise 6–7 days a week | 1.725 |
| Very active | Physical job or twice-daily training | 1.9 |
The factors commonly used with Harris-Benedict and Mifflin-St Jeor. They're estimates; people at the same level can differ by 10–15%.
The two BMR equations
| Equation | Men | Women |
|---|---|---|
| Mifflin-St Jeor (1990) | 10W + 6.25H − 5A + 5 | 10W + 6.25H − 5A − 161 |
| Revised Harris-Benedict (1984) | 88.362 + 13.397W + 4.799H − 5.677A | 447.593 + 9.247W + 3.098H − 4.330A |
W: weight (kg), H: height (cm), A: age (years). Mifflin MD, St Jeor ST et al., Am J Clin Nutr 1990;51:241–247; Roza AM, Shizgal HM, Am J Clin Nutr 1984;40:168–182.
Calorie change by goal
| Goal | Versus TDEE (kcal / day) |
|---|---|
| Lose 0.75 kg / week | − 825 |
| Lose 0.5 kg / week | − 550 |
| Lose 0.25 kg / week | − 275 |
| Maintain | 0 |
| Gain 0.25 kg / week | + 275 |
| Gain 0.5 kg / week | + 550 |
Based on the convention that 1 kg of body fat ≈ 7,700 kcal. In practice weight loss slows because a lighter body burns less.
Examples
Man, 30, 70 kg, 175 cm, moderately active
BMR = 700 + 1,093.75 − 150 + 5 = 1,648.75 kcal; TDEE = 1,648.75 × 1.55 ≈ 2,556 kcal. To lose 0.5 kg a week: about 2,006 kcal, which on the balanced split is about 125 g protein, 67 g fat and 226 g carbs.
Same man with Harris-Benedict
BMR ≈ 1,696 kcal, about 47 kcal higher than Mifflin-St Jeor. The two usually differ by less than 5%.
Woman, 25, 55 kg, 160 cm, lightly active
BMR = 550 + 1,000 − 125 − 161 = 1,264 kcal; TDEE ≈ 1,738 kcal. Losing 0.5 kg a week gives 1,188 kcal, below 1,200, so the calculator warns you; 0.25 kg a week (about 1,463 kcal) is more sensible.
Imperial units: man, 40, 160 lb, 69 in (5 ft 9), lightly active
160 lb = 72.6 kg and 69 in = 175.3 cm, so BMR ≈ 1,626 kcal and TDEE ≈ 2,236 kcal.
Common mistakes
- Picking too high an activity level.
- Walking around the office and light housework still count as sedentary. One level too high can overstate TDEE by 200–300 kcal.
- Adding exercise calories on top of TDEE.
- The activity factor already includes your workouts. Adding what the treadmill shows counts them twice.
- Cutting calories too hard to lose weight fast.
- Eating below roughly 1,200 kcal (women) or 1,500 kcal (men) without medical supervision risks nutrient gaps and muscle loss, and is hard to sustain.
- Judging progress after a few days.
- Weight swings with water, salt and the menstrual cycle. Look at the 2–3 week average trend before adjusting.
Which equation should I use?
A systematic review by Frankenfield and colleagues (J Am Diet Assoc, 2005) found Mifflin-St Jeor predicted resting energy closest to measured values in more people than the other equations, so it's the default here. Revised Harris-Benedict is kept for comparison because many apps still use it.
Neither equation accounts for body composition: very muscular people usually need more than the estimate, and people with obesity may need less.
Who shouldn't rely on these numbers
If you're pregnant or breastfeeding, under 18, a competitive athlete, or have a medical condition (diabetes, kidney or thyroid disease, an eating disorder), get a plan from a doctor or registered dietitian. Results are for reference only; what you enter is calculated in your browser.
Glossary
- Calorie (kcal)
- The unit of food energy; “calories” on food labels are kilocalories.
- BMR
- Basal metabolic rate: the energy your body uses at complete rest to breathe, pump blood and keep warm.
- TDEE
- Total daily energy expenditure: BMR plus activity and digesting food. Eating at TDEE maintains your weight.
- Calorie deficit
- Eating less than TDEE so the body draws on stored energy and you lose weight.
- Macros
- The three energy nutrients: protein 4 kcal / g, carbohydrate 4 kcal / g, fat 9 kcal / g.
Frequently asked questions
How many calories should I eat a day?
It depends on your body and activity: sedentary adults are often around 1,600 – 2,400 kcal. Enter your measurements for your own number.
How many calories make 1 kg?
About 7,700 kcal, so a 550 kcal daily deficit loses roughly 1 kg in two weeks. Progress slows over time.
Should I lose more than 1 kg a week?
Usually not without medical supervision; 0.25 – 0.75 kg a week is easier to sustain and preserves more muscle.
How much should I eat to gain muscle?
Choose gain 0.25 kg a week, eat enough protein (the “Higher protein” split) and do regular strength training so more of the gain is muscle.
What's the right protein, fat and carb split?
The US Institute of Medicine suggests 10–35% of energy from protein, 20–35% from fat and 45–65% from carbs. The “Lower carb” split (40% fat) is outside that range and best kept short-term.
Do you store my weight?
No. Everything is calculated in your browser.
Ratings and comments
Loading…