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 ML In A Mounjaro Pen?
A Mounjaro KwikPen contains approximately 3 ml of solution and delivers four pre-filled doses of tirzepatide — one dose per week for four weeks. Each pen is single-use and cannot be refilled. If you're exploring Mounjaro as a weight management option in the UK, understanding the pen format, cost, and how to access it through NHS specialist services or private prescription is essential. This guide covers everything you need to know about accessing tirzepatide in the UK, from eligibility through to pricing.
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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 Pen Details & UK Private Costs
Each Mounjaro KwikPen is pre-filled and delivers exactly four weekly doses. The pen contains approximately 3 ml of solution, with each injection delivering a specific dose (ranging from 2.5 mg to 15 mg depending on your treatment stage). You cannot reuse or refill a Mounjaro pen — once all four doses are used, you dispose of it and begin a new pen the following week.
UK private prescription costs for Mounjaro typically range from £129 to £320 per month, depending on the dose strength and provider. Lower doses (2.5 mg and 5 mg) are generally less expensive, whilst higher maintenance doses (10 mg, 12.5 mg, 15 mg) cost more. Private costs may include the prescription fee, clinical consultation, and pharmacy dispensing. Always check individual provider pricing, as costs vary between GPhC-registered online pharmacies. Use our GLP-1 weight loss calculator to explore potential outcomes and help inform your decision about whether Mounjaro is right for you.
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.
NHS Access vs Private Routes to Mounjaro
NHS route: Mounjaro is available through NHS specialist tier 3 weight management services following NICE approval. However, access varies significantly by region and ICB (Integrated Care Board). Many areas have substantial waiting lists — sometimes 6–18 months or longer. You'll need a GP referral to a specialist service, which will assess your eligibility and manage your prescription if approved. Availability depends heavily on your local NHS resources.
Private route: You can obtain a Mounjaro prescription privately through a UK-licensed online prescriber without waiting for NHS referral. The process typically involves an online consultation (usually 10–15 minutes), assessment of your medical history, and issuance of a prescription if deemed clinically appropriate. The prescription is then dispensed by a GPhC-registered pharmacy and delivered to your home. This route is faster but involves private costs. Check your BMI using our free BMI calculator to understand your starting point before any consultation.
- 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 much does a Mounjaro KwikPen cost in the UK privately?
Private Mounjaro costs typically range from £129 to £320 per month depending on dose. Lower starting doses (2.5–5 mg) are cheaper; higher maintenance doses (10–15 mg) cost more. Prices vary between providers, so compare quotes before committing.
Can I get Mounjaro on the NHS in the UK?
Yes, Mounjaro is available through NHS specialist weight management services following NICE approval. However, access varies by region and waiting times can be long (6–18+ months in some areas). You'll need a GP referral to a tier 3 specialist service.
How many doses are in one Mounjaro pen?
Each Mounjaro KwikPen contains four pre-filled doses — enough for one month of once-weekly injections. The pen is then disposed of, and a new pen is used the following week.
What's the difference between Mounjaro and Wegovy in terms of access in the UK?
Both require prescription and clinical assessment. Mounjaro is a dual GIP/GLP-1 agonist; Wegovy is a GLP-1 agonist only. NHS access and private costs differ slightly. Use our GLP-1 weight loss calculator to compare projected outcomes between the two.
Do I need a GP referral to get a private Mounjaro prescription online?
No. Private online prescribers can assess you directly without an NHS GP referral. You'll have an online consultation, and if approved, a prescription is issued and dispensed by a pharmacy — typically within days.
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.