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 Qualify for Mounjaro in the UK?
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK, but it's not for everyone. To be eligible, your BMI must meet specific NHS criteria, which vary depending on your health circumstances and ethnicity. Understanding what the BMI range actually means — and the NHS BMI categories that matter — is the first step to knowing whether this medication could be right for you. Check your personal BMI using our free BMI calculator above to see where you currently fall.
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.
NHS BMI Eligibility Criteria for Mounjaro
In the UK, you may be eligible for Mounjaro if:
- Your BMI is 30 or above (classified as obese according to NHS BMI categories), OR
- Your BMI is 27 to 29.9 (overweight) AND you have at least one weight-related health condition
Weight-related health conditions that may qualify you include type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or a history of heart attack or stroke. The healthy BMI range for most UK adults is 18.5 to 24.9, so Mounjaro is considered for those significantly above this threshold.
Importantly, if you have South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply. The NHS recognises that these groups face higher cardiovascular and diabetes risk at lower BMI levels, so eligibility may begin at a BMI of 27.5 or above, even without weight-related health conditions. This ethnicity-adjusted approach reflects best current NHS guidance on metabolic health risk.
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.
The NHS Weight Management Pathway and Getting Mounjaro
Access to Mounjaro through the NHS depends on specialist weight management services, typically at Tier 3 or Tier 4 of the NHS pathway. Your GP can refer you to a specialist service, which will carry out a full clinical assessment before any prescription is issued — they'll check your BMI, health history, medications, and suitability. Waiting times vary significantly by region, and availability is limited in some areas.
If you want faster access or your local NHS service has a long waiting list, prescription Mounjaro is also available through private online prescribing services. A licensed UK prescriber will still assess your BMI and health circumstances before issuing a prescription. Regardless of route, Mounjaro works best alongside a reduced-calorie diet and increased physical activity — BMI alone doesn't determine your success with the medication.
- 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 does a BMI of 28 mean for Mounjaro eligibility?
A BMI of 28 falls in the overweight category (25–29.9). You may be eligible for Mounjaro if you have a weight-related health condition like type 2 diabetes, high blood pressure, or sleep apnoea. If you have South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds apply, so you might qualify even without comorbidities. Check with your GP.
Is BMI the only thing that decides if I can get Mounjaro?
No. While BMI is the primary screening tool, your prescriber will also assess your overall health, medications, and personal circumstances. Conditions like pancreatitis history, thyroid cancer, or pregnancy would exclude you. A full clinical assessment is always required before prescription, not BMI alone.
How do I calculate my BMI to check Mounjaro eligibility?
BMI is calculated as weight (kg) divided by height (metres) squared. Using our free BMI calculator on this page is the quickest way — just enter your weight and height, and it will show you your exact BMI and what NHS category you fall into. You can also use a weight converter to switch between stone and kilograms first.
Can I get Mounjaro on the NHS if my BMI is 29?
At BMI 29, you're in the overweight category. You may qualify for NHS Mounjaro if you have a weight-related health condition. If you have South Asian or other specified heritage, lower BMI thresholds apply. Your GP or a specialist weight management service will assess your full health picture — BMI is just the starting point.
What's the difference between NHS BMI categories and the healthy BMI range?
The healthy BMI range is 18.5–24.9 — this is what the NHS aims for. BMI categories describe broader groups: underweight (below 18.5), overweight (25–29.9), obese (30–39.9), and severely obese (40+). Mounjaro eligibility sits above the healthy range. Note that BMI has limitations — it doesn't account for muscle mass or where fat is stored.
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.