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 Is Needed for Mounjaro in the UK?
In the UK, adults with a BMI of 30 or above may be eligible for Mounjaro (tirzepatide), or those with a BMI of 27–29.9 if they have weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. However, eligibility also depends on individual health assessment and regional NHS availability. Use our free BMI calculator to check your personal BMI instantly, and then discuss your results with your GP to explore whether prescription weight loss treatment might be appropriate for you.
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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.
UK BMI Eligibility Thresholds for Mounjaro
The standard NHS BMI threshold for Mounjaro eligibility is 30 kg/m² or above, which falls into the obese category. However, adults with a BMI of 27–29.9 (overweight category) may also qualify if they have at least one weight-related health condition. These conditions include type 2 diabetes, prediabetes, high blood pressure (hypertension), abnormal blood fats, obstructive sleep apnoea, or a history of cardiovascular disease.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds. These groups typically face higher health risks at lower BMI levels, so eligibility may begin at BMI 27.5 or above. Calculate your BMI range using our BMI calculator and weight converter to understand where you fall within NHS categories and what this means for your health context.
It is important to note that meeting the BMI threshold alone does not assures access to Mounjaro. A prescriber must conduct a clinical assessment to confirm that the medication is suitable for your individual circumstances, medical history, and current health status.
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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.
BMI Limitations and What Else Matters
BMI is a useful screening tool but has important limitations. It does not distinguish between muscle and fat, so athletes or very muscular individuals may have a high BMI despite low body fat. BMI also does not account for where fat is stored — abdominal fat carries higher health risks than fat stored elsewhere.
The NHS also considers waist circumference alongside BMI. For men, a waist measurement over 94 cm (37 inches) indicates increased health risk; over 102 cm (40 inches) indicates high risk. For women, the thresholds are over 80 cm (31.5 inches) and 88 cm (34.5 inches) respectively. Your GP can assess your overall health picture and advise whether weight loss treatment is appropriate for you, regardless of 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 is the exact BMI needed for Mounjaro on the NHS in the UK?
The standard threshold is BMI 30 or above. You may also qualify with BMI 27–29.9 if you have weight-related health conditions like type 2 diabetes or high blood pressure. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds typically apply (BMI 27.5+). A prescriber will assess your individual eligibility.
Can I get Mounjaro on the NHS with a BMI between 27 and 30?
Yes, if you have at least one weight-related health condition such as type 2 diabetes, prediabetes, hypertension, sleep apnoea, abnormal cholesterol, or cardiovascular disease history. Your GP or specialist can assess whether these criteria apply to you and whether Mounjaro is appropriate.
What does a BMI of 30 mean in stone and pounds?
A BMI of 30 depends on your height. For example, at 5ft 8in (173 cm), a BMI of 30 equals approximately 90 kg (14 stone 2 lbs). Use our free BMI calculator and weight converter to find the exact weight corresponding to BMI 30 for your specific height.
Is BMI the only thing considered for Mounjaro eligibility?
No. While BMI is important, prescribers also consider your waist circumference, medical history, current medications, and overall health. You must have a clinical assessment with a licensed prescriber to determine suitability. BMI alone does not assures eligibility or access.
How do I check my BMI and find out about Mounjaro treatment?
Use our free BMI calculator on this page to find your personal BMI. Then discuss your result with your GP, who can refer you to specialist weight management services if appropriate, or you can seek a private clinical assessment through a registered prescriber. Individual results and eligibility vary.
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.