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's the Highest Dose of Mounjaro?
The highest dose of Mounjaro (tirzepatide) available in the UK is 15mg, administered once weekly via a pre-filled KwikPen. This is significantly higher than Wegovy's maximum dose of 2.4mg, reflecting their different mechanisms of action. Both are prescription-only medications requiring a clinical assessment before prescribing. Understanding the maximum dose context, alongside your personal eligibility and health status, helps you and your prescriber decide which medication may be suitable for you.
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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.
Maximum Doses and Dose Titration: Mounjaro vs Wegovy
Mounjaro reaches a maximum of 15mg once weekly, while Wegovy caps out at 2.4mg once weekly. This difference reflects their distinct mechanisms: Mounjaro is a dual GIP and GLP-1 receptor agonist, whereas Wegovy is a GLP-1 agonist only. The higher maximum dose of Mounjaro doesn't necessarily mean greater effectiveness for all individuals—clinical trial data shows results vary significantly. Both medications use gradual dose titration: Mounjaro starts at 2.5mg and increases every 4 weeks if tolerated, while Wegovy starts at 0.25mg with escalation every 4 weeks. SURMOUNT trial data showed Mounjaro at 15mg produced average weight loss of approximately 20.9% body weight, whilst STEP trial data for Wegovy at 2.4mg showed approximately 14.9% average weight loss. However, individual responses differ, and not everyone reaches the maximum dose—prescribers may stabilise patients at lower doses depending on side effect tolerance and clinical response.
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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.
Which Dose Is Right for You?
Your prescriber will determine the appropriate starting dose and titration schedule based on your individual health profile, weight-related conditions, and tolerance. Some patients achieve their weight loss goals at lower doses and may not need to escalate to the maximum. Mounjaro dose titration via KwikPen requires a minimum of 4 weeks at each dose level before increasing. If you experience significant side effects—such as persistent nausea or vomiting—your prescriber may pause escalation or reduce your dose. Both Mounjaro and Wegovy require an NHS UK prescription or private clinical assessment. Use our GLP-1 weight loss calculator to explore potential outcomes at different dose levels, and discuss your personal suitability with your GP or licensed prescriber before starting any medication.
- 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.
Can I jump straight to the highest dose of Mounjaro?
No. Mounjaro must be titrated gradually—starting at 2.5mg and increasing by 2.5mg every 4 weeks. This approach minimises side effects and allows your body to adjust. Jumping to 15mg immediately would increase the risk of severe nausea, vomiting, and gastrointestinal problems.
Why is Mounjaro's maximum dose (15mg) so much higher than Wegovy's (2.4mg)?
The doses reflect their different mechanisms. Mounjaro activates two hormone pathways (GIP and GLP-1), whilst Wegovy targets only GLP-1. This dual action allows Mounjaro to work at higher absolute doses. Direct dose-to-dose comparisons between them are not meaningful.
Is the highest dose of Mounjaro always the most effective?
Not necessarily. Clinical trial averages at 15mg showed greater weight loss than lower doses, but individual results vary widely. Some people reach their weight loss goals at 10mg or 12.5mg. Your prescriber will identify the optimal dose for your situation.
What happens if I can't tolerate Mounjaro's highest dose?
Your prescriber may stabilise you at a lower dose—such as 10mg or 12.5mg—where you experience acceptable side effects and meaningful weight loss. You do not need to reach 15mg for the medication to be effective.
Are Mounjaro and Wegovy NHS-prescribed at their maximum doses?
NHS access to Mounjaro and Wegovy is through specialist tier 3 weight management services and varies significantly by region. When available, NHS prescribers typically follow standard titration protocols, though maximum doses may take 16–20 weeks to reach. Private prescribers follow similar evidence-based titration schedules.
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.