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
Mounjaro Price Rises — How It Compares to Wegovy
As Mounjaro (tirzepatide) prices have risen across UK private providers, many people are comparing it to Wegovy (semaglutide) to understand which medication might offer better value and efficacy. Both are prescription-only weight management injections with different mechanisms, dosing schedules, and clinical trial outcomes. This guide compares them factually so you can have an informed discussion with your GP or prescriber about which might suit your circumstances.
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.
Clinical Evidence — SURMOUNT vs STEP Trials
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways simultaneously. In the SURMOUNT-1 clinical trial, participants on the maximum dose (15 mg) lost an average of approximately 20.9% of their body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity.
Wegovy (semaglutide) is a GLP-1 receptor agonist only (single mechanism). In the STEP-1 clinical trial, participants on the maximum dose (2.4 mg) lost approximately 14.9% of their body weight over 68 weeks under the same lifestyle conditions.
Important: these are clinical trial averages. Individual results vary significantly, and the trial populations, duration, and settings differed. Neither medication assures specific weight loss outcomes. Both require a sustained reduced-calorie diet and physical activity to be effective. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses.
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.
Cost, Dosing, and Practical Differences
Mounjaro typically costs more per month than Wegovy due to manufacturing, research costs, and market positioning — though UK private prices vary. Mounjaro uses once-weekly dosing (2.5 mg to 15 mg over 20+ weeks of titration), while Wegovy also doses once weekly but escalates from 0.25 mg to 2.4 mg over approximately 16 weeks. Both require a UK prescription following a clinical assessment. NHS access is through specialist tier 3/4 weight management services, with significant regional variation. Private access is through GPhC-registered online prescribing services. Your prescriber will assess which medication suits your health profile, BMI, comorbidities, and tolerance — cost alone should not determine suitability. Check your BMI using our BMI calculator to understand your clinical starting point.
- 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.
Why has Mounjaro price risen in the UK?
Mounjaro prices rise due to manufacturing costs, pharmaceutical supply chain factors, and market demand. As more people seek prescription weight management, demand has increased. NHS pricing is fixed; private provider pricing varies and is set by individual pharmacies based on their costs and margin.
Is Mounjaro more effective than Wegovy?
Clinical trials suggest Mounjaro may support slightly higher average weight loss (20.9% vs 14.9%), but individual results vary significantly. Effectiveness depends on your personal response, adherence, diet, and activity level. Your prescriber assesses which is suitable for you based on your health profile, not cost alone.
Can I switch from Wegovy to Mounjaro if prices rise?
Switching between medications must be managed by your prescriber. There is no official established conversion chart between the two. Your GP or weight management specialist can advise on switching if clinically appropriate, but it requires a new assessment and prescription.
Is Mounjaro available on the NHS if private prices are too high?
NHS access to tirzepatide (Mounjaro) is through specialist tier 3/4 weight management services following GP referral. NICE has approved it for NHS use, but availability varies significantly by region (ICB). Waiting times can be several months to over a year in some areas.
What's the difference between tirzepatide and semaglutide?
Tirzepatide (Mounjaro) activates two hormone pathways (GIP + GLP-1), while semaglutide (Wegovy) activates one (GLP-1 only). This dual mechanism may explain why tirzepatide showed higher average weight loss in trials, but both are effective for weight management when combined with lifestyle changes.
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.