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 to Get Mounjaro?
In the UK, you generally need a BMI of 30 or above to be eligible for Mounjaro (tirzepatide). However, if you have weight-related health conditions like type 2 diabetes, high blood pressure, or heart disease, you may qualify with a BMI as low as 27. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, eligibility thresholds are lower due to higher health risks at lower BMI levels. A prescriber will assess your individual eligibility following a clinical evaluation. Use our free BMI calculator to find your personal BMI instantly.
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 BMI Thresholds
Standard eligibility (all adults):
- BMI 30 or above (obesity) — automatically eligible for weight loss treatment assessment
- BMI 27–29.9 (overweight) with at least one weight-related health condition — may qualify
Lower thresholds for specific ethnic groups:
- South Asian, Chinese, Black African, or Black Caribbean adults may be eligible at BMI 27.5 or above, or BMI 23–27.4 with weight-related conditions
These lower thresholds reflect NHS guidance recognising that these populations face higher risks of type 2 diabetes and cardiovascular disease at lower BMI levels compared to white European adults. Your GP or prescriber will assess your individual circumstances using the NHS BMI categories UK framework. Eligibility also depends on having attempted lifestyle changes first and having weight-related health complications. A clinical assessment is always required before Mounjaro can be prescribed.
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 Other Health Measures
While BMI is a useful initial screening tool, it has significant limitations. BMI does not distinguish between muscle and fat — athletes or very muscular individuals may have a high BMI but low body fat percentage. BMI also ignores where fat is stored; excess fat around the stomach (visceral fat) poses greater health risk than fat stored elsewhere. The healthy BMI range for adults is 18.5 to 24.9 according to NHS standards, but your actual health risk depends on multiple factors: waist circumference, blood pressure, cholesterol, blood sugar, family history, and lifestyle. Your GP will consider all these together when assessing whether Mounjaro is appropriate for you. Don't rely on BMI alone — discuss your complete health picture with your healthcare provider.
- 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.
Can you get Mounjaro with a BMI under 30 in the UK?
Yes. If you have a BMI between 27 and 29.9 and have weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea, heart disease, or dyslipidaemia), you may be eligible. A prescriber must assess your individual circumstances.
What counts as a weight-related health condition for Mounjaro eligibility?
Recognised conditions include type 2 diabetes, prediabetes, high blood pressure, abnormal cholesterol levels, obstructive sleep apnoea, and previous heart attack or stroke. Your GP will determine if your conditions qualify.
Do South Asian adults qualify for Mounjaro at a lower BMI?
Yes. NHS guidance acknowledges that South Asian, Chinese, Black African, and Black Caribbean adults have higher cardiovascular and diabetes risk at lower BMI levels. You may be eligible with a BMI of 27.5 or above.
Is BMI the only factor used to decide Mounjaro eligibility?
No. While BMI is a starting point, prescribers also assess your medical history, weight-related conditions, previous weight loss attempts, medications, and overall health. BMI limitations mean your full health picture matters.
How can I check my exact BMI for Mounjaro eligibility?
Use our free BMI calculator on this page to find your BMI instantly using your height and weight. Then check this result against the NHS BMI thresholds and discuss with your GP whether you meet eligibility criteria for weight loss treatment.
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.