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
What Is 5mg Mounjaro Equivalent to in Wegovy?
If you're switching between Mounjaro and Wegovy, or wondering how the doses compare, the approximate equivalent of 5mg Mounjaro is around 0.5mg Wegovy. However, these are not direct equivalents—the medications work differently. Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy is a GLP-1 agonist only. Any medication switch must be managed by your prescriber, as individual dosing depends on your health, response, and tolerance. Both are prescription-only weight management injections licensed in the UK.
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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.
How Do Mounjaro and Wegovy Doses Compare?
Approximate dose equivalence: 5mg Mounjaro is roughly equivalent to 0.5mg Wegovy in terms of potency and clinical effect. However, this is an approximate comparison only—there is no official established conversion chart between the two medications, as they use different mechanisms.
Why the difference? Mounjaro (tirzepatide) activates two hormone pathways (GIP and GLP-1), while Wegovy (semaglutide) activates one (GLP-1 only). This dual mechanism means lower Mounjaro doses may achieve effects comparable to higher Wegovy doses.
- Mounjaro: 5mg dose typically reached by week 5–8 of titration
- Wegovy: 0.5mg dose reached by weeks 5–8 during escalation
- Both are once-weekly injections
- Individual response varies—some people need higher doses
Clinical trials show both medications support weight loss when combined with reduced-calorie diet and increased physical activity. Never adjust doses without prescriber guidance.
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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.
Switching Between Mounjaro and Wegovy: What You Need to Know
If you're considering switching from Mounjaro to Wegovy (or vice versa), this must be managed by your prescriber. They will assess your individual health, current response, side effects, and tolerance before recommending a switch.
Important points: There is no standard conversion protocol—your prescriber may start you on a lower dose and titrate upwards. The switch typically involves stopping one medication and waiting before starting the other. Some people respond better to the dual mechanism of Mounjaro; others prefer Wegovy's single-pathway approach. Try our free GLP-1 weight loss calculator to explore projected outcomes at different doses, and use the BMI calculator to track your progress throughout treatment.
- 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 5mg Mounjaro the same strength as 0.5mg Wegovy?
They are approximately equivalent in potency, but not identical. Mounjaro's dual GIP+GLP-1 mechanism means 5mg may deliver similar effects to 0.5mg Wegovy. However, these are rough equivalences only—individual response varies. Your prescriber will determine the best dose for you based on your health and tolerance.
Can I switch directly from 5mg Mounjaro to Wegovy without stopping?
No. Any medication switch must be managed by your prescriber. You'll typically stop Mounjaro and wait before starting Wegovy to avoid overlapping effects. Your prescriber will advise on timing and the appropriate starting dose for Wegovy based on your individual circumstances.
Why is Mounjaro a lower dose than Wegovy if they're similar in strength?
Mounjaro's dual mechanism (GIP and GLP-1 activation) is more potent than Wegovy's single mechanism (GLP-1 only). This means lower Mounjaro doses can achieve comparable effects to higher Wegovy doses. The two medications cannot be directly compared milligram-for-milligram because they work differently.
What's the maximum dose of Mounjaro compared to Wegovy?
Mounjaro's maximum dose is 15mg once weekly. Wegovy's maximum dose is 2.4mg once weekly. Despite the numerical difference, they are not directly comparable due to different mechanisms of action. Both require prescription and clinical assessment before use.
If Mounjaro isn't working, will Wegovy be more effective?
Not necessarily. Some people respond better to Mounjaro's dual mechanism; others respond better to Wegovy's single-pathway approach. Side effects, personal tolerance, and individual metabolism all affect which medication works better for you. Your GP or prescriber can discuss switching options if needed.
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.