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
Is Mounjaro Cheaper Than Wegovy in the UK?
When comparing GLP-1 weight loss injections in the UK, cost is important — but mechanism and suitability matter more. Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only medications requiring clinical assessment, and pricing varies significantly depending on whether you access them through NHS specialist services or private prescribing. This guide breaks down the key differences to help you understand your options.
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.
How Mounjaro and Wegovy Work Differently
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist. It activates two hormone pathways simultaneously — GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 — which may help regulate appetite and support feeling fuller after smaller meals. The SURMOUNT-1 clinical trial showed participants lost an average of 15–21% of body weight at different doses over 72 weeks, alongside reduced-calorie diet and increased physical activity.
Wegovy (semaglutide) is a single GLP-1 receptor agonist. It activates only the GLP-1 pathway. The STEP-1 clinical trial showed participants lost approximately 15% of body weight at the maximum 2.4 mg dose over 68 weeks, also with diet and exercise changes.
Important context: Individual results vary significantly. The dual mechanism of Mounjaro may provide additional benefit for some people, whilst others respond equally well to Wegovy's single mechanism. A prescriber will assess which suits your individual health profile.
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.
Accessing Mounjaro and Wegovy in the UK — Cost Differences
NHS access: Both medications are NICE-approved and available through NHS tier 3 specialist weight management services. There is no medication cost to you on prescription, though access varies by region and waiting lists can be lengthy. Your GP must refer you to a specialist service — prescribing does not happen in standard GP practice.
Private access: Both are available through UK GPhC-registered online pharmacies following an online clinical assessment. Private costs range from approximately £129–£320 per month depending on dose. Mounjaro and Wegovy often have similar pricing at equivalent dose levels, though individual providers vary. Try our free GLP-1 weight loss calculator above to explore projected outcomes at different doses, then discuss cost and suitability with a prescriber.
Which is right for you? There is no "cheaper" choice in absolute terms — both cost similarly in private prescribing and are free on NHS prescription. Your prescriber will assess your medical history, current medications, weight, BMI (check yours using our free BMI calculator on this page), and any existing health conditions to recommend the most suitable option. Some people are prescribed Mounjaro, others Wegovy, based on individual circumstances — not cost. Always discuss both options with your prescriber and ask which they believe is most appropriate for your specific health profile.
- 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.
Is Mounjaro actually cheaper than Wegovy in the UK?
In private prescribing, Mounjaro and Wegovy usually cost similarly — approximately £129–£320 per month depending on dose and provider. In NHS prescribing, both are free. "Cheaper" depends on dose, supplier, and your individual health circumstances. A prescriber will recommend based on suitability, not cost alone.
What's the difference between Mounjaro's mechanism and Wegovy's?
Mounjaro is a dual GIP+GLP-1 receptor agonist — it activates two hormone pathways. Wegovy is a GLP-1 receptor agonist only — one pathway. Clinical trials suggest Mounjaro may provide slightly higher average weight loss (15–21% vs 15%), though individual results vary significantly.
Can I get Mounjaro or Wegovy on the NHS for free?
Yes, both are NICE-approved and available free on NHS prescription through tier 3 specialist weight management services. You need a GP referral. Availability and waiting times vary significantly by region (ICB). Private prescribing is an alternative if NHS waiting lists are long.
How do I know which medication to ask for — Mounjaro or Wegovy?
A licensed prescriber will assess your medical history, current medications, weight, BMI, and health conditions to recommend which is most suitable. Both require clinical assessment. You cannot simply choose based on cost — suitability is the primary factor. Discuss both options with your prescriber.
What if one medication doesn't work for me — can I switch to the other?
Yes, switching between Mounjaro and Wegovy is possible and is managed by your prescriber. There is no official established conversion chart, but approximate equivalences exist (e.g. Mounjaro 10 mg ≈ Wegovy 1.7 mg). Any switch must be supervised by a prescriber and requires a new clinical assessment.
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.