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- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
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- FAQs answered
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Mounjaro to Wegovy Dose Conversion Chart — UK Guide
If you're considering switching from Mounjaro (tirzepatide) to Wegovy (semaglutide), or comparing the two GLP-1 medications, understanding how their doses relate is important. Both are prescription-only weight management injections available in the UK, but they work differently and use different dosing schedules. This guide explains the approximate dose equivalences, NHS prescribing context, and what you need to know before any medication switch. Always consult your GP or prescriber before making changes to any weight loss medication.
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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 Mounjaro to Wegovy Dose Equivalence
Mounjaro and Wegovy are not directly equivalent — they use different mechanisms and dose ranges, so any conversion is approximate and must be managed by your prescriber. Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy is a GLP-1 agonist only. Clinical trials showed different average weight loss outcomes at their maximum doses (Mounjaro ~20.9% vs Wegovy ~14.9% body weight), reflecting their different potency.
The approximate dose equivalences based on clinical practice are:
- Mounjaro 5 mg ≈ Wegovy 0.5 mg (maintenance)
- Mounjaro 10 mg ≈ Wegovy 1.7 mg (mid-range)
- Mounjaro 15 mg ≈ Wegovy 2.4 mg (maximum)
These are clinical practice guidelines only — there is no official MHRA conversion chart. Your prescriber will assess your individual response and may recommend a different escalation path. Any switch requires a new prescription and clinical review.
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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.
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NHS Eligibility and Prescribing Route for Wegovy
Wegovy (semaglutide 2.4 mg) is approved by NICE and available through NHS specialist tier 3 weight management services. You are eligible if you have a BMI of 30 kg/m² or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, hypertension, dyslipidaemia, or cardiovascular disease. Access is through your GP referral to specialist services, though waiting times vary significantly by region (ICB).
Private prescribing is also available in the UK through online consultations with UK-licensed prescribers, without NHS referral. Use our GLP-1 weight loss calculator to understand projected outcomes, and discuss your UK weight management options with your prescriber — whether NHS or private route.
- 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 more effective than Wegovy?
Clinical trials showed Mounjaro produced slightly higher average weight loss (~20.9% vs ~14.9% body weight). However, both medications vary significantly between individuals. The "better" choice depends on your health profile, individual response, and prescriber assessment. Your GP can advise which is more suitable for you.
Can I switch directly from Mounjaro to Wegovy without stopping?
No — any switch between prescription medications must be managed by your prescriber. You cannot simply switch doses directly. Your prescriber will advise on timing, potential washout periods, and how to safely transition between the two medications based on your individual circumstances.
What's the difference between Mounjaro and Wegovy in the UK?
Mounjaro is a dual GIP and GLP-1 agonist manufactured by Eli Lilly; Wegovy is a GLP-1 agonist only from Novo Nordisk. Both are once-weekly injections. Mounjaro uses doses from 2.5–15 mg; Wegovy escalates from 0.25–2.4 mg. Both require prescription and clinical assessment in the UK.
Does the NHS prescribe Wegovy?
Yes — Wegovy is approved by NICE for NHS use through specialist tier 3 weight management services. Access is via GP referral. However, NHS availability varies by region, and waiting lists can be lengthy. Private prescribing offers faster access in some cases, though you pay privately.
Which dose of Wegovy equals 10 mg Mounjaro?
Approximately 1.7 mg Wegovy is considered clinically equivalent to 10 mg Mounjaro, though this is not an exact conversion. Your prescriber will determine the appropriate starting dose for you based on your health history and response, not purely on dose conversion ratios.
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