How it is calculated
The calculator works out BMR with the Mifflin-St Jeor equation (10 × weight + 6.25 × height − 5 × age, then add 5 for men or subtract 161 for women) and multiplies it by an activity factor:
- Sedentary: 1.2
- Lightly active: 1.375
- Moderately active: 1.55
- Active: 1.725
- Very active: 1.9
The weight loss and weight gain targets are TDEE minus and plus 500 kcal per day. We do not show weight loss targets below 1,200 kcal (women) or 1,500 kcal (men). If TDEE minus 500 is lower, the target is raised to that floor and a “Minimum calorie floor used” row appears.
Many guidelines, including the Malaysian Clinical Practice Guidelines on Management of Obesity (2023), suggest about 1,200 to 1,500 kcal per day for women and 1,500 to 1,800 kcal per day for men for an initial loss of 0.5 to 1 kg per week. Very low calorie diets (under 800 kcal per day) should only be followed under medical supervision. Estimate only, not medical advice.
Worked example
Male, 30 years, 70 kg, 175 cm, moderately active:
- BMR = 1,648.75 (about 1,649 kcal)
- TDEE = 1,648.75 × 1.55 = 2,555.56, shown as 2,556 kcal
- To lose weight: 2,555.56 − 500 = 2,056 kcal
- To gain weight: 2,555.56 + 500 = 3,056 kcal
Female, 25 years, 50 kg, 150 cm, sedentary: BMR = 1,151.5, TDEE = 1,151.5 × 1.2 = 1,382 kcal. TDEE minus 500 is 882 kcal, which is below 1,200, so the weight loss target is shown as 1,200 kcal.
Why your number may differ
Activity factors are commonly used factors, not measured for you, and it is hard to pick the exact level. BMR is also an estimate. A 500 kcal per day difference is a common starting point, not a guarantee. Estimate only, not medical advice. Speak to a doctor or dietitian if you are pregnant, breastfeeding, under 18, have a medical condition or take medication.