BMI if weight changes
Shows how BMI moves for the same height if body weight changes, with shaded BMI category regions for the selected threshold set.
BMIUnderweightUsually healthyOverweightObesity class 1Obesity class 2Obesity class 3
NHS BMI Calculator
A simple adult BMI calculator for forms, reports, and personal records, with NHS-style categories plus context about why BMI is an incomplete measure of health or fitness.
BMI24.8kg/m2
NHS-style categoryUsually healthy range18.5 to 24.9
Healthy-weight range56.7-76.3 kgFor this height and threshold set
Current weight against range
Compares the current weight with the lower and upper healthy-weight reference points for the selected threshold set.
Weight
BMI calculation
Height used1.75 m175 cm
Weight used167.6 lb76 kg
Formulaweight kg / height m squared
Threshold setStandard adult thresholds
Context checks
Age enteredAdult category route.35 years
Context warningStill interpret BMI cautiously and alongside wider context.General adult
Waist-to-heightNot enteredNot entered
Reporting useBMI is often requested in health reports, but it is only one measurement.Useful for forms
Assumptions
Calculation notes
- Independent calculator using NHS-style adult BMI categories. It is not an official NHS service.
- BMI is best treated as one context figure rather than a full health or fitness assessment.
- NHS adult BMI tools are not designed for under-18s, pregnancy, eating disorders, or conditions affecting height.
- BMI can be misleading for people with high muscle mass because it does not distinguish muscle from fat.
- NHS and NICE use lower overweight and obesity thresholds for some Asian, Black African, African-Caribbean, Chinese, and Middle Eastern ethnic backgrounds.
- Health concerns, symptoms, eating concerns, pregnancy, or report-specific requirements are best checked with an appropriate health professional.
Guide
How to use the NHS BMI Calculator
A simple adult BMI calculator for forms, reports, and personal records, with NHS-style categories plus context about why BMI is an incomplete measure of health or fitness. It is useful for checking body-measurement reporting figures or planning training and race-pace scenarios because it keeps inputs, charted outputs, notes, and related next steps on the same page.
Start by checking height unit, height, height feet, height inches, weight unit, and weight. The results update as assumptions change, so you can compare scenarios before downloading a CSV report.
Inputs
Inputs to check
- Height unit: Use either cm or feet/inches. Unused height fields are ignored.
- Height: Enter the value cm you want to test.
- Height feet: Enter the value ft you want to test.
- Height inches: Enter the value in you want to test.
- Weight unit: Use the fields that match the selected unit.
- Weight: Enter the value kg you want to test.
FAQs
NHS BMI Calculator FAQs
What is the NHS BMI Calculator for?
A simple adult BMI calculator for forms, reports, and personal records, with NHS-style categories plus context about why BMI is an incomplete measure of health or fitness. Use it when you want a quick, editable estimate with charted results and visible assumptions.
Which assumptions should I check first?
Start with height unit, height, height feet, height inches, weight unit, and weight. Then review the calculation notes for anything the tool does not include.
Are the results exact?
The result is a planning estimate, not medical, fitness, nutrition, training, or diagnostic advice. Check NHS guidance, a GP, pharmacist, coach, or qualified professional where health or safety matters.
Can I keep or compare the result?
Yes. Use the Download CSV button on the calculator page to export the current inputs, headline results, detailed rows, chart data, insights, and notes.
What should I try next?
Try Race Pace Calculator and Triathlon Pace Calculator next. These tools are linked because they use related assumptions or answer the next practical question.