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 a Healthy BMI Range?
A healthy BMI (body mass index) falls between 18.5 and 24.9 according to NHS guidelines for most UK adults. However, if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a lower healthy BMI range of 18.5 to 22.9, as these groups face higher health risks at higher BMI levels. Your BMI is calculated using your height and weight, and understanding your personal range is an important first step in assessing your overall health. Use our free BMI calculator above to check your individual BMI instantly.
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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 healthy BMI range according to NHS guidelines is 18.5 to 24.9 for most UK adults. This applies regardless of age (though BMI is less accurate in elderly populations). Below this range, you're classified as underweight; above it, you're overweight or obese. However, ethnicity matters significantly:
- South Asian, Chinese, Black African, or Black Caribbean adults: Healthy range is 18.5–22.9 — lower thresholds reflect higher cardiovascular and diabetes risk at higher BMI levels
- Other UK adults: Standard healthy range 18.5–24.9
To calculate your healthy weight for your height, use the BMI formula: weight (kg) divided by height (m)². For example, an adult 1.73m tall has a healthy weight range of approximately 55–74 kg (8st 10lbs to 11st 9lbs). Our BMI calculator above computes this instantly—simply enter your height and weight in your preferred units.
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.
BMI Limitations and What Else Matters
While a healthy BMI range is useful for screening, BMI has important limitations. It doesn't distinguish between muscle and fat—athletes or very fit individuals may have a high BMI but low body fat. BMI also ignores where fat is stored; waist circumference is equally important. The NHS recommends measuring waist circumference alongside BMI: healthy limits are under 94cm (37in) for men and under 80cm (31.5in) for women. Additionally, BMI categories UK are less accurate in older adults due to muscle loss with age, during pregnancy, or in people with significant muscle mass. Your GP can provide personalised health advice based on your individual circumstances, family history, and other health markers beyond BMI alone.
- 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 BMI is considered healthy in the UK?
The NHS defines a healthy BMI range as 18.5–24.9 for most UK adults. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the healthy range is lower at 18.5–22.9 due to higher health risks at higher BMI levels. Use our free BMI calculator to find your personal BMI.
How do I calculate if I'm in a healthy BMI range?
BMI is calculated by dividing your weight in kilograms by your height in metres squared (kg ÷ m²). For example, someone weighing 70kg and 1.75m tall would have a BMI of 23. The easiest method is to use our free BMI calculator above—just enter your height and weight in stone, pounds, or kilograms.
Why are BMI ranges different for some ethnic groups?
Research shows that people of South Asian, Chinese, Black African, and Black Caribbean heritage have higher risk of type 2 diabetes and heart disease at lower BMI levels compared to white European populations. The NHS therefore recommends lower BMI thresholds (18.5–22.9 rather than 18.5–24.9) for these groups to better identify health risk.
What should I do if my BMI is outside the healthy range?
If your BMI is outside the healthy range, speak to your GP. They can assess your individual health, discuss lifestyle changes like diet and exercise, and advise on weight management options if appropriate. Remember that BMI is just one indicator—your GP will consider your overall health picture.
Are there other measures as important as BMI?
Yes. Waist circumference is equally important: the NHS recommends under 94cm for men and under 80cm for women. Overall fitness, diet quality, mental health, and family medical history all matter. BMI doesn't account for muscle mass, so athletes may have high BMI but good health—discuss your personal situation with your GP.
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.