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
How Many Clicks on a 10mg Mounjaro Pen for 5mg?
A Mounjaro 10mg KwikPen contains four pre-filled doses of 2.5mg each, totalling 10mg. To administer a 5mg dose, you need to click the pen twice — once for each 2.5mg increment. This is because each full click on the KwikPen delivers exactly 2.5mg of tirzepatide. Understanding your correct dose is essential, as Mounjaro follows a strict dose titration schedule. Your prescriber will guide you through the injection technique when you start treatment. If you're comparing weight loss options, our GLP-1 weight loss calculator can help you explore potential outcomes at different doses.
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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.
Mounjaro Vs Wegovy: Dose Delivery and Mechanism
Mounjaro (tirzepatide) and Wegovy (semaglutide) are both prescription-only GLP-1-based weight loss injections licensed in the UK, but they work differently and have different dose delivery systems. Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it activates two natural hormone pathways to regulate appetite and blood sugar. Wegovy is a GLP-1 agonist only, activating a single pathway. In clinical trials (SURMOUNT for Mounjaro, STEP for Wegovy), Mounjaro showed average weight loss of approximately 15–21% of body weight, whilst Wegovy showed approximately clinically studied weight loss. Both require a UK prescription following clinical assessment. The KwikPen delivery systems are different: Mounjaro's KwikPen uses click increments (each click = 2.5mg), whilst Wegovy uses a numbered dose selector dial. Neither medication is available on the NHS for routine weight management — access is through specialist weight management services or private prescribing.
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.
Choosing Between Mounjaro and Wegovy: What Your Prescriber Will Consider
Your prescriber will assess which medication suits you based on individual health factors, including your BMI, any weight-related health conditions, current medications, and how you respond to treatment. Both Mounjaro and Wegovy require a BMI of 30 or above, or 27 or above with conditions like type 2 diabetes or high blood pressure, to be eligible. Mounjaro's dual mechanism may be preferred if you have elevated blood glucose levels, whilst Wegovy may be chosen if you're already familiar with GLP-1 treatment. Use our free BMI calculator above to check your starting position, and discuss your prescription options with your GP or prescriber. Individual results vary significantly — some people respond better to one medication than the other. Your prescriber will guide you through the correct injection technique and dose titration for whichever medication is right for you.
- 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.
How many clicks on a Mounjaro 10mg pen equals 5mg?
Two clicks. Each click on the Mounjaro KwikPen delivers 2.5mg of tirzepatide. A 10mg pen contains four pre-loaded 2.5mg doses. To give yourself a 5mg injection, you select the dose dial, press and hold the grey button, and click twice. Your prescriber or pharmacist will demonstrate the correct technique.
Is Mounjaro better than Wegovy for weight loss?
Both are effective prescription weight loss medications, but they work differently. Mounjaro is a dual GIP+GLP-1 agonist; Wegovy is a GLP-1 agonist only. Clinical trial data showed Mounjaro achieved slightly higher average weight loss (up to 21% vs 15%), but individual results vary significantly. Your prescriber will recommend the most suitable option for you.
How long does a 10mg Mounjaro pen last?
A 10mg Mounjaro KwikPen contains exactly four weeks of doses — one 2.5mg injection per week for the first four weeks. As you titrate up to 5mg, 7.5mg, 10mg, 12.5mg, and 15mg over several months, you'll use multiple pens.
Can I switch from Mounjaro to Wegovy or vice versa?
Switching between Mounjaro and Wegovy is possible but must be managed by your prescriber. There is no official established conversion chart — approximate equivalences exist (e.g. Mounjaro 10mg ≈ Wegovy 1.7mg), but any switch requires medical oversight and dose adjustment. Contact your GP or online prescriber for guidance.
Do I need a prescription for Mounjaro in the UK?
Yes. Mounjaro is prescription-only in the UK and cannot be obtained without a clinical assessment. You can access it through NHS specialist tier 3 weight management services (with potentially long waiting lists) or through a private online consultation with a UK-registered prescriber. Always ensure you're using a GPhC-registered pharmacy.
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.