The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Weight and Height BMI Chart — UK NHS Reference
Your weight and height determine your BMI (body mass index), which is the primary health screening tool used by the NHS to assess whether you're in a healthy weight range. Understanding where your weight falls on a BMI chart helps you make informed health decisions and know when to speak with your GP. This guide explains the NHS BMI categories, how to read a weight and height chart, and what the NHS recommends at different BMI levels.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
NHS BMI Categories and Healthy Weight Ranges
The NHS uses the following BMI categories for UK adults:
- Below 18.5 — Underweight
- 18.5 to 24.9 — Healthy weight (recommended range)
- 25.0 to 29.9 — Overweight
- 30.0 to 34.9 — Obese (Class I)
- 35.0 to 39.9 — Obese (Class II)
- 40.0 and above — Severely obese (Class III)
These thresholds apply to most UK adults. However, the NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean heritage, as these groups face higher health risks at lower BMI levels. For these groups, a healthy BMI range is 18.5–22.9, and overweight begins at 23.0. To find your personal BMI instantly using your weight and height, use our free BMI calculator above — it accounts for ethnicity-adjusted thresholds where relevant.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS Weight Management Pathway and When to Seek Help
If your BMI falls outside the healthy range (18.5–24.9), the NHS recommends speaking with your GP. Your GP can assess your individual health, discuss lifestyle changes like diet and physical activity, and refer you to specialist weight management services if needed. The NHS provides a structured pathway: tier 1 covers self-help tools and community programmes; tier 2 involves primary care support; tier 3 offers specialist multidisciplinary services where prescription weight loss treatments may be discussed; tier 4 covers bariatric surgery for severe obesity. Remember that BMI is a screening tool — it doesn't account for muscle mass or where fat is stored. Your GP can provide personalised guidance on what your specific BMI means for your health. Use the weight converter on this page to check your weight in stone, lbs, or kg.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
What is a healthy BMI according to the NHS?
The NHS defines a healthy BMI as between 18.5 and 24.9 for most UK adults. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a lower range of 18.5–22.9. Your GP can advise on what's healthy for you personally based on your age, health conditions, and other factors.
How do I calculate my BMI from my weight and height?
BMI is calculated as weight (kg) divided by height (m) squared. For example, if you weigh 70kg and are 1.73m tall, your BMI is approximately 23.4. Use our free BMI calculator above to find yours instantly — it works with stone, lbs, or kg and shows you which NHS category you fall into.
What should I do if my BMI is above 30?
If your BMI is 30 or above (obese range), the NHS recommends speaking with your GP. Your GP can assess your health, discuss lifestyle changes, and refer you to specialist weight management services if appropriate. Weight management services may include behaviour change support, dietary advice, increased physical activity, and potentially prescription medications or surgery in some cases.
Does BMI account for muscle mass?
No — BMI doesn't distinguish between muscle and fat, so very muscular people may have a high BMI despite low body fat. The NHS also considers waist circumference (increased risk over 94cm for men, 80cm for women) alongside BMI for a fuller health picture. Your GP can assess your overall health beyond just the BMI number.
What's the difference between overweight and obese on a BMI chart?
On an NHS BMI chart, overweight is 25.0–29.9 and obese is 30.0 or above. The obese category is further divided into Class I (30.0–34.9), Class II (35.0–39.9), and Class III/severely obese (40.0+). These distinctions help healthcare professionals assess health risk and plan appropriate support.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.