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
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Is Mounjaro 7.5 Equivalent to Wegovy?
Mounjaro 7.5mg is approximately equivalent to Wegovy 1.7mg based on clinical trial data and clinical practice guidance, though direct dose comparisons are not exact since these medications work slightly differently. Both are prescription-only weight management injections licensed in the UK, but they use different mechanisms: Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy is a GLP-1 agonist only. Individual responses vary, and any switch between medications must be managed by your prescriber following a clinical assessment. Use our free weight loss calculator to explore potential outcomes with different doses.
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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.
Approximate Dose Equivalence Between Mounjaro and Wegovy
Mounjaro (tirzepatide) and Wegovy (semaglutide) are not directly equivalent because they activate different receptor pathways. However, clinical guidance suggests approximate conversions based on weight loss outcomes observed in clinical trials:
- Mounjaro 5mg ≈ Wegovy 0.5–1mg
- Mounjaro 7.5mg ≈ Wegovy 1.7mg (approximate)
- Mounjaro 10–15mg ≈ Wegovy 2.4mg
The SURMOUNT-1 trial showed Mounjaro 10mg achieved approximately clinically studied weight loss, while the STEP-1 trial showed Wegovy 2.4mg achieved approximately clinically studied weight loss. These approximate conversions are based on clinical practice guidance and published trial data. Any switch between medications must be managed by your prescriber — there is no official NHS conversion chart, and individual factors including your response, tolerability, and current dose will determine the most appropriate transition.
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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.
Key Differences Between Mounjaro and Wegovy
While these medications may produce similar weight loss results, they work through different mechanisms. Mounjaro activates both GIP and GLP-1 receptors, which may provide a more potent appetite-suppressing effect for some patients. Wegovy activates GLP-1 only, which is also effective but through a single pathway. Mounjaro's KwikPen device is identical to Ozempic's, while Wegovy uses a separate pre-filled pen. Doses differ significantly: Mounjaro ranges from 2.5–15mg weekly, whereas Wegovy ranges from 0.25–2.4mg weekly. Both are available through NHS specialist weight management services or private prescribing with clinical assessment. Your GP or prescriber can advise which option is more suitable for your individual circumstances.
- 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 7.5mg stronger than Wegovy 1.7mg?
Mounjaro and Wegovy work differently, so direct strength comparison isn't straightforward. Mounjaro's dual GIP/GLP-1 action may produce different results than Wegovy's single GLP-1 mechanism. Individual responses vary significantly. Your prescriber can assess which is more appropriate for you.
Can I switch directly from Mounjaro 7.5mg to Wegovy?
Yes, but this must be managed by your prescriber. Direct switches are not standardised in UK clinical practice. Your prescriber will consider your current response, tolerability, and health profile before recommending any change in medication or dose.
Why are Mounjaro and Wegovy doses so different?
The medications have different potencies and mechanisms. Mounjaro's dual receptor activation means lower doses (mg) achieve comparable effects to Wegovy's higher weekly doses (mg). This is why Mounjaro's maximum is 15mg weekly, whereas Wegovy's is 2.4mg weekly.
Which is more effective — Mounjaro or Wegovy?
Clinical trials show both are effective for weight loss, with average weight loss of 15–21% (Mounjaro) and approximately 15% (Wegovy). Effectiveness varies between individuals based on genetics, diet, exercise, and personal response. Your prescriber will discuss which suits your situation.
Can I get either medication on the NHS in the UK?
Both Mounjaro and Wegovy are available through NHS specialist tier 3 weight management services, though regional availability varies and waiting lists can be lengthy. They're also available privately following an online clinical assessment with a UK-licensed prescriber.
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.