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's the Wegovy Equivalent to Mounjaro 5mg?
There is no exact direct equivalent between Wegovy and Mounjaro 5mg because these are two different medications with different mechanisms of action. Wegovy (semaglutide) is a single GLP-1 receptor agonist, while Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — the dual action in Mounjaro means a lower dose may produce similar results to a higher Wegovy dose. However, approximate clinical equivalence based on weight loss outcomes suggests Mounjaro 5mg may be comparable to Wegovy 0.5mg to 1mg, though individual results vary significantly. Both are prescription-only medicines requiring clinical assessment before prescription in the UK.
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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 Based on Clinical Data
While there is no official established conversion chart between Mounjaro and Wegovy, clinical practice and trial data suggest approximate equivalences:
- Mounjaro 5mg (maintenance dose) may be roughly equivalent to Wegovy 0.5mg to 1mg in terms of weight loss outcome
- Mounjaro 10mg may approximate Wegovy 1.7mg
- Mounjaro 15mg (maximum dose) may approximate Wegovy 2.4mg (maximum dose)
These are approximate only — they are based on clinical trial results and clinical practice guidance, not official pharmaceutical equivalence tables. In the SURMOUNT-1 trial, Mounjaro 5mg produced average weight loss of approximately 15% of body weight, while Wegovy achieved approximately 14.9% in the STEP-1 trial. The key difference is that Mounjaro's dual GIP+GLP-1 mechanism may produce results at lower doses compared to Wegovy's single GLP-1 mechanism. Any dose adjustment or switch between medications must be managed by your prescriber — never attempt to calculate your own equivalent dose.
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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 There's No Exact Equivalence
Mounjaro and Wegovy work through different biological pathways, which is why they cannot be directly converted dose-for-dose. Mounjaro activates both the GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 hormone pathways simultaneously. Wegovy activates only the GLP-1 pathway. This dual action in Mounjaro means the body may respond to a lower dose similarly to how it responds to a higher Wegovy dose — but this varies between individuals based on genetics, metabolism, diet, and exercise.
Additionally, the two medications have different starting doses, titration schedules, and maximum doses. Both are prescription-only and licensed in the UK for weight management in adults with a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Use our GLP-1 weight loss calculator to explore potential weight loss projections at different doses and understand how these medications may support your individual health goals.
- 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 5mg stronger than Wegovy?
Not necessarily "stronger" — it's different. Mounjaro 5mg and Wegovy 0.5–1mg may produce similar weight loss outcomes due to Mounjaro's dual mechanism, but individual responses vary significantly. Clinical trials show both medications support meaningful weight loss, but results depend on your personal metabolism, diet, exercise, and other health factors. Your prescriber will assess which is most suitable for you.
Can I switch from Mounjaro 5mg to Wegovy?
Switching between Mounjaro and Wegovy is possible but must be managed by your prescriber. There is no official conversion protocol — your prescriber will assess whether a switch is clinically appropriate and determine the starting dose. Switching typically involves stopping one medication and starting the other at a lower dose, then titrating up. Never attempt to switch medications on your own.
Which has fewer side effects — Mounjaro or Wegovy?
Both medications have similar common side effects: nausea, diarrhoea, constipation, and stomach pain. Individual tolerability varies — some people experience fewer side effects on one medication than the other. Your prescriber will help monitor your response and adjust your dose or medication if side effects are problematic. Keep a diary of any side effects to discuss with your healthcare provider.
Are Mounjaro and Wegovy both available on the NHS in the UK?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are approved for NHS use through specialist tier 3 weight management services, though access and availability vary significantly by region and NHS integrated care board. Waiting lists can be lengthy. Both are also available privately through UK-licensed prescribers following an online clinical assessment and prescription from a GPhC-registered pharmacy.
Why is Mounjaro sometimes more effective than Wegovy at lower doses?
Mounjaro's dual GIP+GLP-1 mechanism activates two hormone pathways simultaneously, whereas Wegovy (semaglutide) activates only GLP-1. This dual action may produce appetite suppression and metabolic effects at a lower dose. However, both medications support weight loss — the "best" choice depends on your individual health profile, medical history, and how your body responds. Your prescriber will advise based on your personal circumstances.
Ready to take control of your weight loss journey?
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