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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British BMI Chart — NHS Weight Categories Explained
A British BMI chart shows you where your weight falls according to NHS health standards. In the UK, the NHS uses Body Mass Index (BMI) to assess whether an adult's weight is healthy for their height. BMI is calculated using your weight in kilograms divided by your height in metres squared. Unlike other countries, the UK also recognises lower thresholds for certain ethnic groups, including South Asian, Chinese, Black African, and Black Caribbean adults, who face higher health risks at lower BMI levels. Understanding your BMI range is the first step towards managing your weight and improving your health — but it's important to know that BMI has limitations and should be considered alongside other health measures like waist circumference.
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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 provides a clear bmi chart with standard categories for UK adults. These are the official bmi categories uk recognised by the NHS:
- Underweight: BMI below 18.5
- Healthy weight: BMI 18.5 to 24.9
- Overweight: BMI 25.0 to 29.9
- Obese (Class I): BMI 30.0 to 34.9
- Obese (Class II): BMI 35.0 to 39.9
- Severely obese (Class III): BMI 40.0 and above
The bmi range uk for a healthy weight is the same for men and women. However, for adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds: healthy weight is BMI 18.5 to 22.9, and the overweight bmi threshold starts at 23.0 rather than 25.0. This is because research shows these populations have a higher risk of type 2 diabetes and heart disease at lower BMI levels. You can use our free BMI calculator above to find your exact BMI and see which category you fall into instantly.
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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 and When to Seek Help
The NHS offers support across four tiers of weight management. If your BMI puts you in the overweight or obese range, your first step is usually to speak with your GP, who may suggest lifestyle changes like balanced diet and increased physical activity. The NHS also provides free resources including the NHS Weight Loss Plan and digital weight management tools. If you need more intensive support, your GP can refer you to a specialist tier 3 weight management service, which may offer dietitian support, behaviour change programmes, or in some cases, prescription medications. Regional variation exists — some areas have shorter waiting times than others. Our free weight converter can help you track your progress in stone, pounds, or kilograms as you work towards your healthy weight range.
- 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 the healthy BMI range according to NHS guidelines?
The NHS defines healthy weight as a BMI between 18.5 and 24.9 for most UK adults. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the healthy range is slightly lower at 18.5 to 22.9, because these groups face higher disease risk at lower BMI levels.
What does BMI stand for and how is it calculated?
BMI stands for Body Mass Index. The formula is: weight in kilograms divided by height in metres squared. For example, a person weighing 70kg and 1.73m tall would have a BMI of about 23.4. Use our free BMI calculator above for instant calculations.
Why does the NHS give lower BMI thresholds for certain ethnic groups?
Research shows that South Asian, Chinese, Black African, and Black Caribbean adults develop type 2 diabetes, heart disease, and other weight-related health conditions at lower BMI levels compared to other populations. Lower thresholds help identify health risk earlier in these groups.
What are the main limitations of BMI as a health measure?
BMI doesn't distinguish between muscle and fat — athletes may have high BMI but low body fat. It also ignores where fat is stored (waist circumference matters) and doesn't account for age, sex, or bone density. Use BMI alongside other measurements like waist circumference for a fuller picture.
How do I get NHS support if my BMI is in the overweight or obese range?
Start by speaking with your GP, who can assess your health and discuss options. The NHS weight management pathway includes self-help tools (tier 1), primary care support (tier 2), specialist services (tier 3), and surgery (tier 4). Your GP can refer you to appropriate support based on your needs and local availability.
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.