Body and weight
Calculators for BMI, waist to height, body fat and how your measurements change, in stone or kilos, using NICE ranges.
Featured calculator
BMI calculator
Stone and pounds or kilos, the NHS bands and the NICE lower thresholds if they apply to you. A good first number, though never the whole story.
Work out my BMITakes about a minute
Most used
Where most people start
The four body and weight calculators that get the most use.
Waist to height ratio
Body fat
Healthy weightSearch
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Everything
All 36, sorted into shelves
Grouped by what you want to find out. Every one is in the new design.
Weight and BMI
Your BMI, a healthy weight range and how a change adds up.
8 calculators8 in the new design
- BMIWork out your Body Mass Index in stone, pounds and feet.Open
- Ideal weightFour classic ideal weight formulas, next to the NHS range.Open
- Healthy weightThe healthy weight range for your height, in stone or kilos.Open
- Stone and pounds converterStone and pounds to kilos and back, exact factors.Open
- Weight maintenance rangeA calorie range to keep your weight steady, quieter to busier weeks.Open
- Athlete BMI checkCheck a high BMI against your waist.Open
- BMI for Asian backgroundsYour BMI on the NICE lower thresholds of 23 and 27.5.Open
- BMI plus waist risk explainerBMI and waist size read together, using the NICE risk table.Open
Waist and shape
A tape measure tells you more than the scales.
10 calculators10 in the new design
- Waist to height ratioNICE says keep your waist under half your height. Check yours.Open
- Waist to hip ratioWaist divided by hips, against the WHO cut-offs.Open
- Body frame sizeSmall, medium or large frame, from your wrist and height.Open
- Body shapeHourglass, pear, rectangle and more, for choosing clothes.Open
- Healthy waist sizeYour waist against the WHO sizes: 37 in for men, 31.5 in for women.Open
- Clothing size estimateYour likely UK dress, top or trouser size from a tape measure.Open
- Metric to imperial body measurement converterCm, inches, kilos, pounds, stone, metres and feet, any direction.Open
- Body measurement symmetryLeft and right measurements compared, with the DVT warning signs.Open
- Tape measure accuracy helperAverage two or three readings and check they agree.Open
- Height comparisonYour height against the UK average and against someone else.Open
Body fat and make up
Fat, muscle and lean mass, estimated.
8 calculators8 in the new design
- Body fatBody fat from a tape measure, with the healthy range for your age.Open
- Lean body massYour muscle, bone, organs and water, as lean body mass.Open
- Body surface areaBody surface area by the Mosteller and Du Bois formulas.Open
- Body typeHeath-Carter body type, starting from height and weight.Open
- Body composition goal plannerThe weight that matches a body fat goal, kept within healthy limits.Open
- Body density estimateThree skinfolds into body density and body fat (Jackson-Pollock).Open
- Resting metabolism from lean massResting energy from lean mass, by Katch-McArdle and Cunningham.Open
- Muscle to fat ratioYour weight split into lean and fat, and the ratio between them.Open
Tracking change
Before and after, without obsessing.
10 calculators10 in the new design
- Weight change percentageHow much your weight has moved, as a percentage, up or down.Open
- Target weight dateRoughly when you would reach a weight, at a steady pace.Open
- Before and after measurement trackerWaist, hips, chest, thigh and arm, then and now.Open
- BMI change over timeYour BMI then and now, and what one point means for you.Open
- Weight loss percentageThe share of your starting weight lost, with your 5% and 10% marks.Open
- Weight gain percentageHow much you have gained, as a percentage and per week.Open
- Healthy weight pace checkerYour average weekly change against the NHS 0.5 to 1 kg a week.Open
- Bags of sugar weight changeYour weight change, pictured as 1 kg bags of sugar.Open
- Weight plateauHow much your energy need has dropped since you started.Open
- Weight fluctuationA week of weigh-ins averaged, with the day to day swing.Open
Good to know
Where the numbers come from
About these numbers
Guidance, not a diagnosis
NICE now suggests pairing BMI with your waist to height ratio, because where you carry weight matters as much as how much there is. Keeping your waist under half your height is a simple target.
Sources
Where we get them
- NHSHealth A to Z and the NHS BMI calculator
- NICE NG246Overweight and obesity guideline, 2025
- UK Chief Medical OfficersPhysical activity and alcohol guidelines
- SACNScientific Advisory Committee on Nutrition
Last checked 21 October 2026. Each calculator lists its own sources too.
Help
If your weight is on your mind
Talk to your GP if your weight has changed a lot without trying, or if it is worrying you. If food or your body feels hard to think about, Beat has a free helpline on 0808 801 0677 (England, weekdays 3pm to 8pm).
Goals
Got a goal in mind?
Guided plans that walk you through the right calculators in the right order, with NHS guidance along the way.
Reach a healthy weight