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 the Correct BMI for Your Health?
There's no single "correct" BMI for everyone—but the NHS provides clear healthy BMI ranges based on your height and weight. A healthy BMI falls between 18.5 and 24.9 according to NHS guidelines, though for adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds starting at 18.5 to 22.9. Your individual correct BMI depends on your age, ethnicity, muscle mass, and overall health. Understanding your BMI is a useful first step in assessing your health, but it's just one piece of the picture. Let's explore what the NHS recommends and how to find your correct BMI range.
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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 BMI Ranges
The NHS BMI formula is straightforward: weight in kilograms divided by height in metres squared. The result places you into one of five BMI categories UK adults should understand:
- Underweight: BMI below 18.5
- Healthy weight: BMI 18.5–24.9 (the correct, healthy range)
- Overweight: BMI 25.0–29.9
- Obese (Class I): BMI 30.0–34.9
- Severely obese (Class III): BMI 40.0 and above
For most UK adults, a healthy BMI between 18.5 and 24.9 represents the correct target range. However, the NHS recognises that certain ethnic groups face higher health risks at lower BMI levels, so overweight BMI threshold adjustments apply: South Asian, Chinese, Black African, and Black Caribbean adults should aim for a BMI range of 18.5–22.9. Your GP can help you determine what the correct BMI range is specifically for you based on your individual circumstances.
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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: When to Seek Help
The NHS offers a structured approach to weight management across four tiers. If your BMI falls outside the healthy range, your first step is usually your GP, who can offer lifestyle advice and may refer you to NHS weight management programmes. The NHS recognises that a correct approach to weight loss involves support tailored to your needs. For BMI over 30, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure, you may qualify for specialist tier 3 services, where medication and intensive support are available. Use our free BMI calculator above to check your personal BMI instantly, then speak with your GP about next steps if needed. Many people find that understanding their correct BMI is the first motivation for positive change.
- 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 normal, correct BMI for adults in the UK?
A healthy, correct BMI for most UK adults is between 18.5 and 24.9, according to NHS guidelines. For South Asian, Chinese, Black African, or Black Caribbean adults, the NHS recommends a healthy BMI of 18.5–22.9 due to higher health risks at lower BMI levels. Your GP can advise on your specific target range.
How do I calculate my correct BMI?
The BMI formula is: weight (kg) ÷ height (m)². For example, if you weigh 70kg and are 1.73m tall, your BMI = 70 ÷ (1.73)² = 23.4, which is in the healthy range. Use our free BMI calculator on this page for gradual improvement.
Is BMI the only measure of correct health weight?
No. BMI is a useful screening tool but has significant limitations—it doesn't distinguish between muscle and fat, doesn't account for where fat is stored, and varies by age and ethnicity. The NHS also recommends measuring waist circumference: over 94cm for men or 80cm for women indicates increased health risk, regardless of BMI.
What should I do if my BMI is outside the healthy range?
Start by talking to your GP, who can discuss lifestyle changes like diet and exercise. If your BMI is 30 or above, or 27–29.9 with weight-related conditions, you may qualify for NHS specialist weight management services. Your GP can refer you to tier 2 or tier 3 support in your area.
Is the correct BMI the same for children?
No. Children's BMI uses age and sex-specific centile charts, not adult categories. The NHS recommends using the UK90 growth reference charts for children. Ask your health visitor or GP to assess your child's healthy weight using the correct paediatric BMI assessment method.
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.