PlainwrenTDEE and calorie calculator
Enter your age, sex, height, weight and how active you are to estimate how many calories your body uses in a day. Use it as a starting point, then adjust based on how your weight actually changes.
How it is calculated
First the calculator estimates your basal metabolic rate (BMR): the energy your body uses at complete rest. It uses the Mifflin-St Jeor equation, published in 1990 in the American Journal of Clinical Nutrition (Mifflin, St Jeor and others), which is widely used by dietitians:
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
Then it multiplies BMR by an activity factor to get your total daily energy expenditure (TDEE), the calories you use on a typical day including movement and exercise:
| Activity level | Multiplier |
|---|---|
| Sedentary (little or no exercise) | 1.2 |
| Lightly active (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 (very hard exercise or physical job) | 1.9 |
These multipliers are the conventional ones used with BMR equations. They are rough: most people overestimate how active they are, so if unsure, pick the lower level.
If you enter a body fat percentage, the calculator uses the Katch-McArdle equation instead, which is based on lean body mass: BMR = 370 + 21.6 × lean mass (kg), where lean mass = weight × (1 − body fat % ÷ 100). It is only as good as your body fat measurement.
Imperial inputs are converted exactly: 1 lb = 0.45359237 kg and 1 inch = 2.54 cm.
Worked example
A 30-year-old man who weighs 80 kg and is 180 cm tall: BMR = 800 + 1,125 − 150 + 5 = 1,780 kcal a day. Moderately active, his TDEE is 1,780 × 1.55 = 2,759 kcal a day.
A 30-year-old woman who weighs 65 kg and is 165 cm tall: BMR = 650 + 1,031.25 − 150 − 161 = 1,370 kcal. Lightly active, her TDEE is about 1,370 × 1.375 ≈ 1,884 kcal.
Losing or gaining weight
The results also show TDEE minus and plus 500 kcal a day. A common rule of thumb says this changes weight by about 0.5 kg (1 lb) a week, based on roughly 7,700 kcal per kg of body fat. In practice weight change slows over time as your body adapts, so treat it as a rough guide and adjust after a few weeks based on real results.
Assumptions and limits
- For adults aged 18 and over. It is not suitable for children, teenagers, or during pregnancy or breastfeeding.
- Equations give an average for people like you; an individual's real BMR can be 10% or more above or below the estimate.
- Very muscular people may be underestimated by Mifflin-St Jeor, because it only uses total weight; Katch-McArdle with an accurate body fat figure may suit them better.
- The formula uses sex as a biological variable. If neither option describes you well, the two results give a range.
FAQ
What is the difference between BMR and TDEE?
BMR is what you would burn lying still all day. TDEE adds everything else: walking, work, exercise and digesting food. TDEE is the number to compare with what you eat.
Why do other calculators give different numbers?
They may use another equation (such as Harris-Benedict) or different activity multipliers. Differences of 100–200 kcal are normal; none of them is exact.
How do I convert kcal to kJ?
1 kcal = 4.184 kJ. The results show both.
Not medical advice. This calculator gives a general estimate only. If you have a medical condition, take medication, are pregnant, or plan a large change in what you eat, talk to a doctor or registered dietitian first.