How this calculator works
This tool combines three common estimates. BMI (body mass index) compares your weight to your height: it is your weight in kilograms divided by your height in metres squared (kg / m²). It is a quick screening number, not a measure of body fat. BMR (basal metabolic rate) is roughly how many calories your body burns at rest, and TDEE (total daily energy expenditure) scales that up by how active you are.
For BMR we use the Mifflin-St Jeor equation, widely regarded as one of the more reliable formulas. For men it is 10 × kg + 6.25 × cm − 5 × age + 5; for women it is 10 × kg + 6.25 × cm − 5 × age − 161. Your TDEE is then BMR × activity multiplier. If you enter imperial units, the tool converts internally using 1 inch = 2.54 cm and 1 pound = 0.4536 kg.
| BMI range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
Reference note: a daily deficit of about 500 calories corresponds to roughly 1 pound (about 0.45 kg) of weight change per week, since around 3,500 calories is often used as an approximate figure for a pound of body fat. Real-world results vary with metabolism, water balance and other factors. This is informational only and not medical advice.
Frequently asked questions
- What is BMI and how is it calculated?
- BMI (body mass index) estimates body weight relative to height. It is weight in kilograms divided by height in metres squared (kg / m²). Under 18.5 is underweight, 18.5–24.9 normal, 25–29.9 overweight, and 30 or above obese. It is a general screening estimate, not medical advice.
- What is BMR?
- BMR (basal metabolic rate) is the calories your body burns at rest to keep basic functions running. This tool uses the Mifflin-St Jeor equation: men 10 × kg + 6.25 × cm − 5 × age + 5; women 10 × kg + 6.25 × cm − 5 × age − 161.
- What is TDEE?
- TDEE (total daily energy expenditure) estimates the calories you burn per day including activity. It is your BMR multiplied by an activity factor — about 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 active and 1.9 very active.
- How many calories should I eat to lose weight?
- As a general estimate, eating about 500 calories per day below your TDEE creates roughly a 1 pound per week deficit. This is informational only; individual needs vary, so consult a qualified professional before changing your diet.
- Is BMI accurate for everyone?
- No. BMI does not account for muscle mass, bone density, body composition or build, so very muscular people may read as overweight while others within a normal BMI may carry excess fat. Treat it as one general indicator, not a diagnosis.
- Is this medical advice?
- No. This calculator provides general, informational estimates only and is not medical advice. For guidance about your weight, diet or health, consult a qualified healthcare professional.