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
Free tracker included with every download this week
What Is Normal BMI? NHS Data and UK Health Ranges
Normal BMI ranges in the UK follow NHS guidelines, with a healthy BMI sitting between 18.5 and 24.9 for most adults. However, if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends slightly lower thresholds due to increased health risks at lower weights. Understanding where your BMI falls helps you assess your health status, though BMI is just one tool—waist measurement and overall fitness matter too. Use our free BMI calculator above to find your personal BMI instantly and see where you sit within the NHS categories.
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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 Thresholds
The BMI formula is straightforward: weight (kg) divided by height (m) squared. According to NHS guidance, BMI results fall into clear categories that help assess health risk.
- Below 18.5: Underweight — may indicate insufficient nutrition or underlying health concerns
- 18.5–24.9: Healthy weight — optimal range for most adults
- 25.0–29.9: Overweight — increased health risk begins
- 30.0–34.9: Obese (Class I) — significant health risk
- 35.0–39.9: Obese (Class II) — higher health risk
- 40.0+: Severely obese (Class III) — very high health risk
For South Asian, Chinese, Black African, or Black Caribbean adults, the healthy BMI range is 18.5–22.9, with overweight starting at 23.0. This reflects NICE and NHS guidance recognising higher cardiovascular and diabetes risk in these populations at lower BMI levels.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 Support and When to Seek Help
The NHS offers a structured weight management pathway across four tiers. Tier 1 includes self-help tools and community programmes—MyWeightCheck's free BMI calculator and weight converter fit here, helping you understand your baseline. Tier 2 involves primary care support from your GP, including behaviour change advice. Tier 3 is specialist multidisciplinary weight management services, where prescription medications like GLP-1 injections may be considered. Tier 4 is bariatric surgery for severe obesity with significant complications. See your GP if: your BMI is consistently above 30, you have weight-related health conditions, or you're struggling with sustainable weight loss despite lifestyle efforts.
The NHS uses BMI limitations alongside other measures for comprehensive assessment. BMI doesn't distinguish muscle from fat—athletes may have high BMI but low body fat. Waist circumference is equally important: men should aim below 94cm (37 inches), women below 80cm (31.5 inches). Age, ethnicity, and medical history all affect how BMI is interpreted. Your GP can provide personalised guidance on what your BMI means for your health and whether intervention is needed. Use our free weight converter to track measurements in different units, and our GLP-1 weight loss calculator if you're exploring prescription weight management options with NHS services.
- 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 normal BMI range according to NHS guidelines?
The NHS defines a healthy BMI as 18.5–24.9 for most UK adults. For people of South Asian, Chinese, Black African, or Black Caribbean descent, the healthy range is 18.5–22.9 due to higher health risks at higher BMI in these groups.
Why does the NHS recommend different BMI thresholds for certain ethnic groups?
Research shows that people of South Asian, Chinese, and Black African/Caribbean heritage have higher risk of type 2 diabetes, heart disease, and other conditions at lower BMI levels. NHS and NICE guidance reflects this evidence to ensure equitable health assessment across all populations.
What BMI qualifies someone for NHS weight management treatment?
Generally, a BMI of 30 or above, or 27–29.9 with weight-related health conditions (diabetes, hypertension, sleep apnoea), may qualify for specialist NHS support. Lower thresholds apply for certain ethnic groups. Your GP can assess eligibility and refer you to tier 3 services.
Is BMI the only measure the NHS uses to assess weight and health?
No. The NHS also measures waist circumference and considers overall fitness, medical history, and ethnicity. BMI has limitations—it doesn't account for muscle mass or fat distribution. Your GP will use multiple measures for a complete health picture.
How do I find my NHS BMI category and healthy weight range?
Calculate your BMI using our free BMI calculator above—it instantly shows your personal BMI and NHS category. For a personalised healthy weight range based on your height, ask your GP or use NHS weight management tools available through your local health service.
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.