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 Average BMI in the UK?
The average BMI in the UK is around 27.5 for adults, placing most of the population in the overweight category according to NHS guidelines. However, average doesn't mean healthy — a healthy BMI sits between 18.5 and 24.9. Understanding where your BMI falls and what it means for your health is important. Use our free BMI calculator above to check your personal BMI instantly and see how it compares to NHS recommendations for your age and height.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Understanding BMI Categories and UK Averages
According to NHS data, the average BMI for UK adults is approximately 27.5, with men averaging around 27.9 and women around 27.4. This means the typical UK adult falls into the overweight category (BMI 25.0–29.9), not the healthy weight range. The BMI formula divides weight in kilograms by height in metres squared, giving a standardised measurement. NHS BMI categories are: underweight (below 18.5), healthy weight (18.5–24.9), overweight (25.0–29.9), obese class I (30.0–34.9), obese class II (35.0–39.9), and severely obese (40.0+). For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI range UK thresholds due to higher health risks at lower BMI levels. Even though population averages are above the healthy range, individual healthy BMI targets should be based on personal health factors, not population statistics.
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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.
BMI Limitations and What Matters Beyond the Number
While BMI is a useful screening tool, it has important limitations. BMI limitations include the fact that it doesn't distinguish between muscle and fat — athletes may have a high BMI but low body fat. BMI also doesn't account for age, bone density, or where fat is stored around your body. Waist circumference is equally important: the NHS recommends men keep waist measurements under 94cm (37 inches) and women under 80cm (31.5 inches) for health. Combining BMI assessment with waist measurement, blood pressure, and cholesterol gives a much clearer picture of cardiovascular health than BMI alone. Your GP can offer personalised guidance on what a healthy weight means for you specifically.
- 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 average BMI in the UK?
The average BMI for UK adults is approximately 27.5, placing most people in the overweight category. Men average 27.9 and women 27.4. However, healthy BMI according to NHS guidelines is 18.5–24.9, so population average is higher than recommended.
Is an average BMI of 27 healthy?
No. An average BMI of 27 falls in the overweight category (25.0–29.9) rather than the healthy range (18.5–24.9). Average doesn't equal healthy. Your personal healthy BMI target depends on your individual health, not population statistics.
How do I calculate my BMI?
BMI = weight in kilograms ÷ (height in metres)². For example, someone weighing 70kg and 1.73m tall would have BMI = 70 ÷ (1.73)² = 23.4. Our free BMI calculator on this page does this instantly for you.
Why is BMI average higher in the UK than healthy targets?
Rising obesity rates mean population averages have shifted upward over recent decades. However, NHS health targets remain based on cardiovascular and metabolic health evidence, not population norms. Higher average doesn't change what's medically recommended.
What should I do if my BMI is above the healthy range?
Speak to your GP for personalised advice. Even a 5–10% weight reduction can improve health markers. The NHS recommends gradual, sustainable weight loss of around 0.5–1kg per week alongside balanced diet and physical activity. Your GP can discuss whether you'd benefit from support or weight management services.
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.