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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What Is 1 Mg Wegovy Equivalent To Mounjaro?
1 mg Wegovy (semaglutide) is approximately equivalent to 2.5–5 mg Mounjaro (tirzepatide) in clinical effect, though direct dose comparisons are not straightforward because these medications work through different mechanisms. Wegovy is a GLP-1 receptor agonist, while Mounjaro is a dual GIP and GLP-1 receptor agonist. Both are prescription-only weight management injections licensed in the UK, but they require individual clinical assessment before prescribing, and switching between them should only be managed by a healthcare professional.
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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.
Understanding Dose Equivalence Between Wegovy And Mounjaro
There is no officially established conversion chart between Wegovy and Mounjaro doses, as they use different mechanisms to support weight management. However, clinical practice suggests approximate equivalences based on average weight loss outcomes in trials:
- 1 mg Wegovy (mid-escalation dose) may be roughly equivalent to 2.5–5 mg Mounjaro in overall clinical effect
- 1.7 mg Wegovy (escalation dose) may align with 5–7.5 mg Mounjaro
- 2.4 mg Wegovy (maintenance dose) may approximate 10–15 mg Mounjaro
These are approximate clinical estimates only, not official equivalences. Individual response to each medication varies significantly. In STEP trials, Wegovy at 2.4 mg produced average weight loss of approximately 14.9% of body weight. Mounjaro trials showed average loss of 15–20.9% depending on dose. Your GLP-1 weight loss calculator can help project outcomes, but only a prescriber can assess which medication and dose is appropriate for your individual health profile.
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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.
Why These Medications Are Not Directly Equivalent
Wegovy and Mounjaro work through different biological pathways, which is why direct dose equivalence is complex. Wegovy (semaglutide) is a GLP-1 only receptor agonist—it activates one hormone pathway that reduces appetite and supports satiety. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, activating two pathways simultaneously, which may explain why some people experience greater weight loss or different side effect profiles. If you are considering switching between these medications, your GP or weight management specialist must manage the transition. Both require a UK prescription following clinical assessment. Using our BMI calculator can help establish your baseline health metrics, but medication choice depends on individual factors including medical history, current treatments, and previous response to similar drugs.
- 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 Wegovy (semaglutide) stronger than Mounjaro (tirzepatide)?
No single medication is universally "stronger." Mounjaro's dual mechanism may produce slightly greater average weight loss in clinical trials, but individual results vary widely. Some people respond better to Wegovy, others to Mounjaro. Clinical assessment by a prescriber determines which is appropriate for you. Both are prescription-only medications.
Can I switch from Wegovy to Mounjaro without medical guidance?
No. Any switch between prescription weight loss medications must be managed by your prescriber or GP. Switching requires stopping one medication safely and starting the other at appropriate doses. Never attempt self-managed transitions between these injections—your healthcare professional will assess timing, dosing, and any interactions with other medications.
Why is there no official Wegovy to Mounjaro conversion chart in the UK?
Because they work through different mechanisms (single vs. dual receptor activation), there is no NHS or MHRA standard conversion. Dose equivalence is based on clinical practice estimates, not regulatory guidance. This is why prescriber assessment is essential—they will base decisions on your individual response, not just dose comparison.
Which medication is prescribed more often on the NHS UK?
Mounjaro is the more recently approved tirzepatide option and is increasingly integrated into NHS specialist weight management services (tier 3 and 4). Availability varies by region and ICB. Private prescribing for both Mounjaro and Wegovy is available alongside NHS access through specialist referral.
What should I do if I'm unsure whether Wegovy or Mounjaro is right for me?
Discuss with your GP or weight management specialist. Both are prescription-only and require clinical assessment of your BMI, health conditions, medications, and medical history. Use our free BMI calculator to establish your baseline, but let a healthcare professional determine which medication—if any—is appropriate for your individual circumstances.
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.