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
Mounjaro and Wegovy Dosage: How Do They Compare?
If you're considering prescription weight loss treatment in the UK, understanding the dosage differences between Mounjaro (tirzepatide) and Wegovy (semaglutide) is important. Both are once-weekly injections licensed for weight management, but they work differently and use different dosing schedules. This guide compares the mg dosage levels, how they're titrated, and what the clinical trial data shows. Individual suitability depends on your personal health circumstances—your prescriber will assess which option is appropriate for you following a clinical assessment.
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.
Mounjaro vs Wegovy: Dosage Schedules and Starting Doses
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist with a starting dose of 2.5 mg per week, escalating to a maximum of 15 mg per week. The dose titration occurs over approximately 20 weeks, with increases of 2.5 mg every four weeks if tolerated: 2.5 mg (weeks 1–4), 5 mg (weeks 5–8), 7.5 mg (weeks 9–12), 10 mg (weeks 13–16), 12.5 mg (weeks 17–20), and 15 mg (week 21 onwards).
Wegovy (semaglutide) is a GLP-1 receptor agonist only, with a lower starting dose of 0.25 mg per week, escalating to 2.4 mg per week over approximately 17 weeks. The titration schedule is: 0.25 mg (weeks 1–4), 0.5 mg (weeks 5–8), 1 mg (weeks 9–12), 1.7 mg (weeks 13–16), and 2.4 mg (week 17 onwards).
The key difference: Mounjaro starts higher and escalates more gradually, whilst Wegovy uses smaller increments over a similar timeframe. Both require a clinical assessment before prescription via NHS specialist services or private online prescribing in the UK.
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.
Clinical Trial Results: What the Data Shows
In the SURMOUNT-1 trial, Mounjaro at 15 mg achieved average weight loss of approximately 20.9% of body weight over 72 weeks when combined with a reduced-calorie diet and increased physical activity. The STEP-1 trial for Wegovy at 2.4 mg showed average weight loss of approximately 14.9% over 68 weeks under similar conditions.
Important context: these are clinical trial averages—individual results vary significantly. Some people respond better to one medication than another. The dual mechanism of Mounjaro (GIP + GLP-1) differs from Wegovy's single GLP-1 pathway, which may account for differences in average outcomes. However, this does not assures superior results for any individual. Your prescriber will assess which is more suitable based on your health profile, medical history, and any other medications you take.
- 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 starting dose of Mounjaro in mg?
The starting dose of Mounjaro is 2.5 mg once weekly. Your prescriber will assess whether to increase this after a minimum of 4 weeks, typically escalating in 2.5 mg increments up to a maximum of 15 mg per week. Dosage is personalised based on tolerance and response.
What's the maximum Wegovy dose in mg?
The maximum Wegovy dose is 2.4 mg once weekly. Most people reach this maintenance dose after 17 weeks of titration, starting from 0.25 mg. Your prescriber may recommend staying at a lower dose if that achieves your health goals and is well tolerated.
Why does Mounjaro have higher mg doses than Wegovy?
Mounjaro (tirzepatide) uses higher mg doses because it's a dual GIP and GLP-1 agonist, whilst Wegovy (semaglutide) is a GLP-1 agonist only. The different mechanisms and chemical structures require different dosing schedules. Both are effective—the choice depends on individual suitability assessed by your prescriber.
Can you switch between Mounjaro and Wegovy dosages?
Switching between Mounjaro and Wegovy should only be done under prescriber guidance. Whilst approximate equivalences exist (e.g. Mounjaro 10 mg ≈ Wegovy 1.7 mg), there is no official conversion chart. Any change in medication requires a new clinical assessment and prescription.
How do I use the MyWeightCheck tools to track my medication?
Use our free GLP-1 weight loss calculator to project potential outcomes at different Mounjaro or Wegovy doses. Our BMI calculator helps you track your starting point and progress, and our progress tracker lets you log weekly weight changes to monitor how the medication is working for you personally.
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.