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- 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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Wegovy Equivalent to Mounjaro: Doses and Differences
If you're exploring GLP-1 weight loss medications in the UK, you may wonder how Wegovy compares to Mounjaro and whether there's a direct dose equivalent between them. While both are prescription-only injectable treatments for weight management, they work differently and have different dose ranges. This guide breaks down the approximate equivalence, mechanism differences, and clinical trial data to help you understand what your prescriber might recommend. Use our free GLP-1 weight loss calculator to explore potential outcomes with different medications.
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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 and Key Differences
There is no official established dose conversion between Wegovy (semaglutide) and Mounjaro (tirzepatide), but clinical practice guidelines suggest approximate equivalences based on mechanism and trial results:
- Mounjaro 5 mg ≈ Wegovy 0.5 mg — early maintenance doses
- Mounjaro 10 mg ≈ Wegovy 1.7 mg — mid-range doses
- Mounjaro 15 mg ≈ Wegovy 2.4 mg — maximum doses
The key difference is mechanism: Mounjaro is a dual GIP and GLP-1 receptor agonist (activating two hormone pathways), while Wegovy is a GLP-1 agonist only (single pathway). In clinical trials, Mounjaro produced slightly higher average weight loss (up to 20.9% at 15 mg) compared to Wegovy (approximately 14.9% at 2.4 mg), though individual results vary significantly. Your UK prescriber will assess which is more suitable based on your health profile, not dose alone.
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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.
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Clinical Trial Data and Individual Suitability
Wegovy's weight loss data comes from the STEP trials, showing average loss of approximately 14.9% of body weight at the maximum 2.4 mg dose over 68 weeks. Mounjaro's data comes from the SURMOUNT-1 trial, showing average loss of 20.9% at 15 mg over 72 weeks. However, these are averages — some people lose more, some less. Both medications are prescription-only and require a clinical assessment before being prescribed. There is no standard reason to prefer one over the other based solely on dose numbers; your GP or prescriber will consider your medical history, other medications, and individual health factors. Use our BMI calculator to establish your baseline, then discuss medication suitability with a licensed prescriber.
- 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 stronger than Wegovy?
Mounjaro showed slightly higher average weight loss in clinical trials (20.9% vs 14.9%), but this reflects trial averages, not individual outcomes. Mounjaro uses a dual GIP+GLP-1 mechanism versus Wegovy's single GLP-1 mechanism. "Stronger" is misleading — suitability depends on your health profile and how your body responds, assessed by your prescriber.
What's the exact Mounjaro to Wegovy conversion?
There is no official conversion chart. Approximate clinical equivalences are: 5 mg Mounjaro ≈ 0.5 mg Wegovy, 10 mg ≈ 1.7 mg, and 15 mg ≈ 2.4 mg. These are rough guides only. Any switch between medications must be managed by your prescriber, never attempted alone.
Can I switch from Wegovy to Mounjaro in the UK?
Yes, you can discuss switching with your prescriber. Both are UK-licensed for weight management. Your prescriber may switch you if Wegovy hasn't worked as expected, or if they believe Mounjaro's dual mechanism suits you better. The switch requires clinical assessment — you cannot simply change doses.
Which weight loss injection is available on the NHS?
Both Mounjaro and Wegovy are approved for NHS specialist weight management services, though availability varies significantly by region (ICB). Waiting lists can be lengthy. Private prescription is available through licensed UK prescribers and GPhC-registered pharmacies without NHS referral.
How long does each medication take to work?
Weight loss typically begins within the first 4 weeks as you titrate upward, but meaningful change often takes 8–12 weeks as you reach therapeutic doses. Both require continued use and lifestyle changes (diet and physical activity) to maintain results. Results vary individually.
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.