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
Free tracker included with every download this week
Wegovy Dose Equivalent to Mounjaro: What You Need to Know
Wegovy and Mounjaro are both prescription-only weight management injections available in the UK, but they work through different mechanisms and use different dose ranges. Wegovy (semaglutide) is a GLP-1 receptor agonist, whilst Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist. There is no official NHS-endorsed conversion chart between the two, but approximate dose equivalences exist based on clinical practice and trial data. This guide explains how doses roughly compare and why any switch between medications must be managed by your prescriber. Use our free GLP-1 weight loss calculator to explore potential outcomes at different dose levels for either medication.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Wegovy and Mounjaro
Approximate equivalence table (based on clinical practice, not official guidance):
- Wegovy 0.5 mg ≈ Mounjaro 5 mg
- Wegovy 1.7 mg ≈ Mounjaro 10 mg
- Wegovy 2.4 mg ≈ Mounjaro 15 mg
These are rough clinical estimates only. Wegovy reaches its maximum maintenance dose of 2.4 mg over 17 weeks, while Mounjaro escalates to 15 mg over approximately 20 weeks. The dual mechanism of Mounjaro (GIP + GLP-1) versus Wegovy's single GLP-1 mechanism means clinical outcomes differ between individuals even at approximate dose equivalents. In SURMOUNT-1 trials, Mounjaro at 15 mg produced average weight loss of approximately 20.9% body weight, whilst Wegovy at 2.4 mg (STEP-1 trials) showed average weight loss of approximately 14.9% body weight. Both medications are prescription-only and require a clinical assessment before prescribing. Never switch between medications without your prescriber's guidance.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 Exact Conversion Doesn't Exist and How to Switch
There is no official dose conversion formula because Wegovy and Mounjaro have different pharmacological profiles, different titration schedules, and different maximum doses. Your prescriber must assess whether switching is clinically appropriate for your individual health, current dose, tolerance, and response. If considering a switch from one medication to another, discuss with your GP or the prescriber managing your weight loss treatment. They may recommend a gradual transition, dose adjustment, or may suggest continuing your current medication if it is working well for you. Any switch should account for your personal tolerance, side effect profile, and weight loss progress to date. Use our free BMI calculator to track your health metrics alongside your prescriber's recommendations.
- 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.
What's the difference between Wegovy and Mounjaro?
Wegovy (semaglutide) is a GLP-1 receptor agonist that activates one hormone pathway. Mounjaro (tirzepatide) is a dual agonist activating both GIP and GLP-1 pathways. This dual mechanism may contribute to Mounjaro's slightly higher average weight loss in trials, though individual results vary significantly.
Can I switch from Wegovy to Mounjaro?
Yes, switching is possible, but only under prescriber guidance. Your GP or weight management specialist will assess whether switching is appropriate based on your tolerance, current response, and health. Never stop or switch medications without medical advice.
Is Mounjaro stronger than Wegovy?
Mounjaro's dual mechanism (GIP + GLP-1) produced higher average weight loss in clinical trials compared to Wegovy's single GLP-1 mechanism. However, individual outcomes vary significantly, and suitability depends on your personal health profile, not just theoretical strength.
How long does the titration schedule differ between the two?
Wegovy reaches maximum dose (2.4 mg) in approximately 17 weeks. Mounjaro reaches maximum dose (15 mg) in approximately 20 weeks. Both are once-weekly injections, but the dose escalation pace differs slightly.
Do I need a new prescription to switch between the two medications?
Yes. Switching from Wegovy to Mounjaro (or vice versa) requires a new NHS or private prescription from a UK-licensed prescriber following a clinical assessment. You cannot simply swap without medical guidance.
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.