Free UK BMI Calculator (NHS-Standard)
Calculate your BMI instantly in kg, cm, stones, pounds, feet or inches — using the same WHO/NHS formula your GP uses. Plus 12 more health calculators covering children, pregnancy, muscle mass, body fat, calories and ideal weight.
Calculate Your BMI
Enter your height and weight to instantly calculate your Body Mass Index and understand your health category.
Select your gender
BMI Chart & Categories
Understanding your BMI category helps you assess potential health risks and set appropriate wellness goals.
| BMI Range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obese Class I |
| 35.0 – 39.9 | Obese Class II |
| 40.0+ | Obese Class III |
More Health Calculators
Explore our full suite of free, evidence-based health calculators. From body fat and calories to ideal weight — get a comprehensive understanding of your body metrics.
BMI Calculator (Kg)
Metric-locked: kilograms and centimetres, WHO/NHS formula
Open calculatorBMI Calculator (Stones)
UK imperial: stones, pounds, feet and inches
Open calculatorBMI Calculator with Age & Gender
Age- and gender-adjusted healthy ranges for teens, women, men, and seniors
Open calculatorBMI Calculator with Muscle Mass
Lean BMI (FFMI) — calculate BMI for athletes, muscular adults and gym-goers
Open calculatorNHS BMI Calculator
NHS-style BMI check with NICE ethnicity-adjusted thresholds
Open calculatorReverse BMI Calculator
Set a target BMI, get the exact weight in kg, lbs, or stones
Open calculatorHow to Calculate BMI
The WHO/NHS formula explained in metric, imperial & Excel
Open calculatorChild BMI Calculator
Ages 2 to 19 — CDC age-and-sex percentile bands
Open calculatorBMI Calculator for Pregnancy
Calculate BMI when pregnant — IOM/NICE weight-gain ranges (singleton & twin)
Open calculatorBody Fat Calculator
Body fat percentage via the US Navy circumference method
Open calculatorCalorie Calculator
Daily calorie needs for loss, maintenance, or gain (Mifflin-St Jeor)
Open calculatorIdeal Weight Calculator
Four clinical formulas — Robinson, Miller, Devine, Hamwi
Open calculator
What Is BMI? A Complete Guide to Body Mass Index
Learn what BMI is, how it's calculated, what your BMI score means, and why it matters for your health. Comprehensive guide with charts and categories.
BMI vs Body Fat Percentage: Which Matters More?
Compare BMI and body fat percentage as health metrics. Understand the pros and cons of each measurement and when to use them.
Healthy Weight Ranges by Age & Height
Find your healthy weight range based on your age, height, and gender. Includes detailed charts and expert recommendations.
How to Reduce Body Fat: Science-Backed Strategies
Evidence-based strategies to reduce body fat while maintaining muscle mass. Learn about nutrition, exercise, and lifestyle changes.
Calories & Weight Loss: How Many Do You Need?
Understand the relationship between calories and weight loss. Learn how to calculate your calorie needs and create a sustainable deficit.
Heart Health and BMI: What the Research Shows
Explore the connection between BMI and cardiovascular health. Learn how maintaining a healthy BMI can reduce heart disease risk.
Frequently Asked Questions
Common questions about BMI and our health tools.
Track Your Health Journey
Sign up for free to save your BMI results, track changes over time, and get personalized health insights.