BMI Calculator UK
Calculate your BMI in kg, stone or pounds, then estimate BMR, TDEE, waist risk, body fat and daily macro targets on the same page.
This tool is for adults who want a quick, plain-English way to understand weight, calorie needs and body composition estimates. Results update instantly as you type and stay in your browser.
What this calculator is for
Use one page for the common weight and calorie checks people usually search for separately.
- BMI: a height-and-weight screening estimate, shown to no more than one decimal place.
- BMR and TDEE: estimated resting calories and estimated daily calorie needs.
- Waist and body composition: waist risk, waist-to-hip ratio, body fat and skinfold estimates.
- Daily macros: estimated protein, carbohydrate and fat targets from your calorie goal.
Use the number as a guide, not a diagnosis
BMI is useful because it is quick, but it cannot see muscle mass, pregnancy, age-related body changes, ethnicity, symptoms, medication or medical history. Waist measurement and clinical judgement can matter too.
BMR, TDEE and macro figures are estimates. Real calorie needs vary with activity, sleep, hormones, illness, medication and body composition.
BMI 24.8 • Healthy range
Choose your preferred units first.
BMI, BMR and TDEE Calculator
Start with a simple BMI result, then add age, sex and activity level for calorie estimates.
Body Composition Tools
Use waist, hip, neck or skinfold measurements to add context beyond BMI.
Daily Macro Calculator
Estimate daily protein, carbohydrate and fat targets from your calorie goal.
We take your daily calorie target and apply the macro split you choose. Protein and carbohydrate are estimated at 4 kcal per gram, and fat is estimated at 9 kcal per gram.
BMI guidance and source links
For medical context, compare your result with recognised public-health guidance and use BMI as one part of the picture, not the whole picture.
Useful next reads
If your result is part of a wider weight-loss or maintenance plan, these guides may help you understand next steps, costs and expectations.
BMI and TDEE questions
What is BMI?
BMI means body mass index. It compares your weight with your height and gives a quick adult screening estimate. It is useful, but it does not measure body fat directly.
Why does BMI only show one decimal place?
BMI is only an estimate, so extra decimal places can make it look more precise than it really is. One decimal place is easier to read and more sensible for normal use.
Should I use BMI or waist measurement?
Use both if you can. BMI gives a quick height-and-weight estimate, while waist measurement can give extra context about central body fat and possible health risk.
Can this calculator tell me if I qualify for treatment?
No. Treatment suitability depends on more than a calculator result. A regulated clinician may consider BMI, health conditions, medication, medical history, safety checks and prescribing guidance.
Is this calculator for children?
No. This page is written for adults. Children and teenagers need age-specific BMI interpretation, so use a child-specific calculator or ask a healthcare professional.