BMI — Body Mass Index
A single number that compares your weight to your height. A quick screening for under/normal/over-weight categories.
kg / m²
BMI & Calorie Calculator
Calculate your Body Mass Index (BMI) and daily calorie needs (TDEE) with the clinically-recommended Mifflin-St Jeor equation. Switch between metric and imperial units, pick from 5 activity levels.
Units:
Enter all values above.
BMR — Basal Metabolic Rate
Calories required at complete rest — to power your heart, brain, and breathing. Mifflin-St Jeor (1990).
10·W + 6.25·H − 5·A ± C
TDEE — Total Daily Energy
BMR × activity factor (1.2 sedentary → 1.9 very active). Your actual daily calories to maintain weight.
BMR × activity
Healthy weight by height
Weight ranges for normal, overweight, and obese categories per WHO (BMI 18.5–24.9 / 25–29.9 / ≥30).
| Height | Normal | Overweight | Obese (≥30) |
|---|---|---|---|
| 160 cm / 5'3" | 47 – 64 kg | 64 – 77 kg | ≥ 77 kg |
| 165 cm / 5'5" | 50 – 68 kg | 68 – 81 kg | ≥ 82 kg |
| 170 cm / 5'7" | 53 – 72 kg | 72 – 86 kg | ≥ 87 kg |
| 175 cm / 5'9" | 57 – 76 kg | 77 – 92 kg | ≥ 92 kg |
| 180 cm / 5'11" | 60 – 81 kg | 81 – 97 kg | ≥ 97 kg |
| 185 cm / 6'1" | 63 – 85 kg | 86 – 102 kg | ≥ 103 kg |
| 190 cm / 6'3" | 67 – 90 kg | 90 – 108 kg | ≥ 108 kg |
Frequently asked questions
What is BMI and how is it calculated?
Body Mass Index is your weight in kilograms divided by your height in metres squared: BMI = kg / m². For someone weighing 70 kg at 1.75 m: 70 / (1.75 × 1.75) = 22.9.
What are the WHO BMI categories?
The World Health Organization classification: underweight (< 18.5), normal weight (18.5–24.9), overweight (25–29.9), obesity class I (30–34.9), class II (35–39.9), and class III (≥ 40).
Is Mifflin-St Jeor more accurate than Harris-Benedict?
Yes. The Mifflin-St Jeor equation (1990) is generally regarded as more accurate than the original Harris-Benedict (1919) or its 1984 revision. The Academy of Nutrition and Dietetics recommends it for estimating calorie needs in healthy adults.
What is TDEE and how does it differ from BMR?
BMR (basal metabolic rate) is the calories your body needs at complete rest — to power your heart, brain, and breathing. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor (1.2–1.9 depending on lifestyle), and it reflects your actual daily calorie needs.
How big a calorie deficit do I need to lose weight?
A deficit of about 500 kcal/day produces a loss of ~0.45 kg (1 lb) per week — the rate most clinicians consider safe and sustainable. Larger deficits speed loss but risk muscle loss; do not drop below ~1200 kcal/day for women or ~1500 kcal/day for men without medical supervision.
What are the limitations of BMI?
BMI cannot distinguish muscle from fat, does not capture fat distribution (visceral vs subcutaneous), and is invalid for children, pregnant women, athletes, and adults over 65. For those groups, waist circumference, body-fat %, or a DEXA scan give better information.
Are my inputs stored anywhere?
No. Every calculation runs entirely in your browser — no requests are sent and nothing is saved.