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 Are the BMI Criteria for Mounjaro in the UK?
Mounjaro (tirzepatide) is available in the UK for adults who meet specific BMI thresholds set by healthcare regulators. The main criterion is a BMI of 30 or above, or a BMI of 27–29.9 if you have at least one weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds due to higher health risks at lower BMI levels. Your GP or a licensed prescriber will assess whether you meet the criteria during a clinical consultation.
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.
BMI Thresholds and Eligibility Categories
Standard BMI criteria for Mounjaro eligibility in the UK:
- BMI 30 or above: You may be eligible regardless of other health conditions
- BMI 27–29.9 with weight-related health conditions: You may be eligible if you have type 2 diabetes, prediabetes, high blood pressure (hypertension), abnormal blood fats (dyslipidaemia), obstructive sleep apnoea, or a history of heart attack or stroke
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the thresholds are lower due to evidence that these groups face greater cardiovascular and metabolic risk at lower BMI levels:
- BMI 27.5 or above: You may be eligible
- BMI 23–27.4: You may be eligible if you have weight-related health conditions
Use our free BMI calculator above to check your personal BMI instantly based on your height and current weight in stone, pounds, or kilograms.
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 Supporting Assessments
BMI is a screening tool, not the complete picture. BMI does not distinguish between muscle and fat — athletes may have a high BMI but low body fat. Your prescriber will assess your overall health, including waist circumference (waist-to-height ratio), existing health conditions, and medications, alongside your BMI when deciding eligibility. The NHS emphasises that a healthy waist-to-height ratio (below 0.5) is also important, as belly fat carries greater health risks than fat stored elsewhere. You can convert your weight between kg and stone using our free weight converter to help track your measurements accurately during your assessment.
- 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 minimum BMI for Mounjaro in the UK?
The minimum BMI for Mounjaro is 30 kg/m² in most cases, or 27–29.9 if you have weight-related health conditions like type 2 diabetes or high blood pressure. For South Asian, Chinese, Black African, or Black Caribbean adults, the threshold is lower at 27.5 kg/m² due to higher metabolic risk in these groups.
Can I get Mounjaro on the NHS if my BMI is 28?
If your BMI is 28 and you have a qualifying weight-related health condition (type 2 diabetes, hypertension, sleep apnoea, or cardiovascular disease), you may be eligible. If you're of South Asian or similar heritage, the threshold is even lower. Always discuss your individual circumstances with your GP or prescriber.
How do I calculate my BMI to check Mounjaro eligibility?
BMI is calculated as weight in kilograms divided by height in metres squared. Use our free BMI calculator on this page — simply enter your height and weight in stone, pounds, or kilograms, and it will calculate your BMI and show where you fall on the NHS healthy BMI range chart.
Does BMI alone determine Mounjaro eligibility?
No. While BMI is the primary screening measure, your prescriber will also assess your waist circumference, existing health conditions, blood pressure, cholesterol, and other factors. BMI doesn't account for muscle mass or fat distribution, so a full health picture is considered during your clinical assessment.
What if my BMI is just below the Mounjaro threshold?
If your BMI is slightly below 30, discuss your circumstances with your GP. If you have weight-related health conditions or metabolic risk factors, you may still qualify. Prescribers also consider your overall health trajectory and medical history, not just the BMI number itself.
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.