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 BMI Do You Need for Mounjaro in the UK?
In the UK, you may be eligible for Mounjaro (tirzepatide) if you have a BMI of 30 or above, or a BMI between 27 and 29.9 with at least one weight-related health condition. However, eligibility depends on individual assessment by a healthcare professional. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply. Use our free BMI calculator above to check your personal BMI instantly, and speak with your GP or a licensed prescriber to discuss whether Mounjaro is suitable for you.
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.
UK Mounjaro Eligibility Based on BMI Range
The primary BMI requirement for Mounjaro in the UK is a BMI of 30 or above, which falls into the obese category according to NHS guidelines. However, you may also be eligible with a lower BMI if you have weight-related health conditions. Specifically:
- BMI 30 and above: Eligible without other conditions
- BMI 27–29.9 with health conditions: Eligible if you have type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, sleep apnoea, or cardiovascular disease history
- South Asian, Chinese, Black African, or Caribbean adults: Lower thresholds apply due to higher health risks at lower BMI levels — eligibility may start at BMI 27.5 or above
These are NHS-aligned criteria. Your prescriber will assess your individual circumstances, not just your BMI number. Convert your weight to check where you fall using our weight converter, and calculate your exact BMI with our BMI calculator to see where you sit within these ranges.
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 BMI is the starting point for Mounjaro eligibility, it is important to understand that BMI has limitations. BMI does not distinguish between muscle and fat — athletes or very muscular individuals may have a high BMI but low body fat. BMI also doesn't account for where fat is stored (belly fat carries higher health risks) or your overall fitness level.
Your GP or prescriber will also consider your waist circumference, blood pressure, blood sugar levels, cholesterol, and medical history. These factors combined give a much fuller picture of your health risk than BMI alone. Even if your BMI falls within the eligible range, your prescriber may recommend lifestyle changes first, or may determine that Mounjaro is appropriate for you. Always have a conversation with your healthcare professional about what these measurements mean for your individual health.
- 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 do I need to qualify for Mounjaro on the NHS in the UK?
On the NHS, you typically need a BMI of 30 or above, or 27–29.9 with a weight-related health condition like type 2 diabetes, high blood pressure, or sleep apnoea. Access is through specialist tier 3 weight management services, and availability varies by region. Your GP can advise on local services and referral criteria.
Is my BMI of 28 enough to get Mounjaro?
A BMI of 28 falls into the overweight category. You may be eligible if you have a qualifying health condition such as type 2 diabetes, hypertension, or cardiovascular disease. However, eligibility is assessed individually. Speak with your GP or a licensed prescriber about your specific circumstances and whether Mounjaro is appropriate for you.
Does Mounjaro BMI requirement differ for people of South Asian or Black African heritage?
Yes. The NHS recommends lower BMI thresholds for adults of South Asian, Chinese, Black African, Black Caribbean, and other high-risk groups because they face higher risk of type 2 diabetes and heart disease at lower BMI levels. Eligibility may begin at BMI 27.5 or above rather than 30. Your prescriber will apply the correct threshold for your background.
What if my BMI is above 30 but I have no health conditions — can I get Mounjaro?
Yes, a BMI of 30 or above alone meets the primary criterion for Mounjaro eligibility in the UK, regardless of other conditions. However, you will still need a clinical assessment from a prescriber to confirm it is suitable for you. They may recommend lifestyle changes first, or may decide Mounjaro is the right choice for your circumstances.
Do I need to stay at the eligible BMI to continue taking Mounjaro?
No. Once Mounjaro treatment has been initiated and you begin losing weight, your BMI will drop. You do not need to stop the medication when your BMI falls below the initial eligibility threshold. Your prescriber will manage your treatment as your weight changes and monitor your response over time.
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.