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 and Mounjaro Dose Equivalence
Wegovy (semaglutide) and Mounjaro (tirzepatide) are two different prescription weight loss injections available in the UK, and they work in different ways. While there is no official conversion chart between them, approximate dose equivalences exist based on clinical practice. This guide explains how the doses compare and what you need to know if you're considering either medication for weight management.
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
Although Wegovy and Mounjaro are not interchangeable medications, approximate dose equivalences have emerged from clinical practice and trial data. These comparisons help healthcare professionals understand relative strength across the two GLP-1 and GIP/GLP-1 medication classes:
- Mounjaro 5 mg is roughly equivalent to Wegovy 0.5 mg in terms of weight loss potential
- Mounjaro 10 mg is roughly equivalent to Wegovy 1.7 mg
- Mounjaro 15 mg (maximum Mounjaro dose) is roughly equivalent to Wegovy 2.4 mg (maximum Wegovy dose)
These equivalences are approximate only. The actual effectiveness and side effect profile can vary significantly between individuals. Any switch between medications must be managed by your prescriber—never attempt to transfer doses without clinical guidance. Individual response differs based on metabolism, body composition, existing health conditions, and tolerance to GLP-1 or GIP/GLP-1 medications.
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 the Doses Aren't Directly Comparable
Wegovy (semaglutide) activates only the GLP-1 receptor, whereas Mounjaro (tirzepatide) activates both the GIP and GLP-1 receptors—a dual mechanism. This fundamental difference means they work slightly differently in your body. Mounjaro's dual action may produce stronger appetite suppression at lower doses, which is why the dose ranges differ: Mounjaro goes up to 15 mg weekly, while Wegovy reaches 2.4 mg weekly. Neither dose is "better"—the right choice depends on your individual health profile, how your body responds, and your prescriber's assessment. Use our GLP-1 weight loss calculator above to explore potential weight loss projections at different doses.
- 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 because the doses are higher?
Not necessarily. Mounjaro's higher numerical dose reflects its different mechanism (dual GIP/GLP-1 vs single GLP-1 only). In clinical trials, Mounjaro produced slightly higher average weight loss (~20.9% at 15 mg) compared to Wegovy (~14.9% at 2.4 mg), but individual results vary significantly. Strength depends on how your body responds, not just the dose number.
Can I switch from Wegovy to Mounjaro using the equivalent dose?
No. Any switch between these medications must be managed by your prescriber. They will assess your individual response, side effects, and health profile before recommending a new medication and starting dose. There is no standard conversion protocol—your prescriber will guide the transition carefully to ensure safety.
What's the difference between Mounjaro and Ozempic?
Both contain semaglutide, but Ozempic is licensed for type 2 diabetes management (up to 2 mg), whereas Wegovy is the licensed weight loss version (up to 2.4 mg). Ozempic is not approved for weight loss in the UK—using it for that purpose would be off-label. Always ask your prescriber which version is right for you.
Will I lose the same amount of weight on the equivalent doses?
Not necessarily. Even at approximately equivalent doses, individual weight loss varies due to genetics, metabolism, lifestyle factors, diet, activity level, and how your body responds to the medication. Clinical trials show average outcomes, but your personal results may differ. Track your progress with our free progress tracker to monitor your individual response.
How do I know which medication is right for me—Wegovy or Mounjaro?
Your prescriber will assess your medical history, current health conditions, existing medications, and any allergies or contraindications. They'll also consider factors like injection frequency preference (both are weekly), your response to GLP-1 medications if you've used them before, and whether the dual GIP/GLP-1 mechanism of Mounjaro may be beneficial for you. A clinical assessment is essential before prescription.
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.