Two of the most searched health questions online are "what is my BMI?" and "how many calories should I eat?". This page answers both — with free built-in calculators and clear explanations of what the numbers actually mean for your health.
Based on the Mifflin-St Jeor equation. Values are estimates — consult a healthcare provider for personalised advice.
BMI (Body Mass Index) is a simple number calculated from your height and weight. It was developed in the 1830s by Belgian mathematician Adolphe Quetelet and is now used worldwide as a quick screening tool for weight-related health risks.
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Nutritional deficiency, bone loss, immune issues |
| 18.5 – 24.9 | Normal weight | Lowest risk for most adults |
| 25.0 – 29.9 | Overweight | Elevated risk of heart disease, type 2 diabetes |
| 30.0 – 34.9 | Obese (Class I) | High risk, medical consultation recommended |
| 35.0 – 39.9 | Obese (Class II) | Very high risk |
| 40.0 and above | Obese (Class III) | Extremely high risk, immediate action advised |
The formula is simple:
Example: You weigh 75 kg and are 1.75 m tall.
In imperial units: BMI = (weight in lbs × 703) ÷ (height in inches)²
Your body burns calories even at rest — to breathe, pump blood, and maintain body temperature. This is called your Basal Metabolic Rate (BMR). Your total daily energy expenditure (TDEE) accounts for your activity level on top of BMR.
Then multiply by your activity factor:
| Activity Level | Multiplier | Example |
|---|---|---|
| Sedentary | × 1.2 | Desk job, no exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days/week |
| Moderately active | × 1.55 | Moderate exercise 3–5 days/week |
| Very active | × 1.725 | Hard exercise 6–7 days/week |
| Extra active | × 1.9 | Physical job + daily training |
One kg of body fat contains approximately 7,700 calories. To lose 0.5 kg per week, you need a daily deficit of about 550 calories. The safest approach:
To gain lean muscle mass, eat 250–500 calories above your TDEE and combine with strength training. Gaining too fast (1,000+ kcal surplus) results mostly in fat gain. Aim for 0.25–0.5 kg per week for lean bulk.
| BMI | Body Fat % | |
|---|---|---|
| Measures | Weight relative to height | Actual fat tissue proportion |
| Equipment needed | Just a scale and tape measure | DEXA scan, calipers, or bioimpedance |
| Accuracy | Population-level screening | More precise for individuals |
| Limitation | Can't distinguish muscle from fat | Harder to measure accurately at home |
| Best use | Quick health check | Fitness tracking, body composition goals |
For adults, 18.5–24.9 is considered healthy. For children and teenagers, BMI is interpreted differently using age- and sex-specific growth charts. Use the calculator above for your personal BMI.
It depends on your age, sex, height, weight, and activity level. Use the calorie calculator above — it uses the Mifflin-St Jeor equation, which is the most accurate formula for most adults. Average ranges: women 1,600–2,400 kcal, men 2,000–3,000 kcal.
A 500 kcal/day deficit leads to roughly 0.5 kg (1 lb) of fat loss per week and is generally considered safe and sustainable for most healthy adults. Deficits above 1,000 kcal/day should only be done under medical supervision.
No — BMI cannot distinguish muscle from fat. A bodybuilder may have a BMI of 30 (classified as obese) while having very low body fat. For athletic populations, body fat percentage is a more meaningful measure.
Basal Metabolic Rate is the calories your body burns at complete rest. Think of it as the minimum fuel your organs need. Your TDEE (total daily energy expenditure) is BMR multiplied by your activity level — it's the number you should base your diet around.