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
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How Many mls In A Mounjaro Dose — UK Guide
Each Mounjaro KwikPen contains 0.5 ml of solution, regardless of the dose strength you're prescribed. The dose is measured in milligrams (mg), not millilitres — so a 5 mg dose and a 15 mg dose both use the same pen volume. This guide explains Mounjaro dose strengths, what's in each pen, UK pricing for private access, and how to get prescribed through the NHS or online consultation routes.
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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 Dose Strengths & Pen Contents
Mounjaro is supplied as a pre-filled KwikPen auto-injection device. Each pen contains 0.5 ml of solution, but the strength varies by dose level. The active ingredient is tirzepatide, which works as a dual GIP and GLP-1 receptor agonist.
Doses available in the UK include: 2.5 mg (starting dose), 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg (maximum dose). Each dose is injected once weekly, and your prescriber will typically increase your dose every 4 weeks if needed. The pen itself is identical across all dose strengths — the difference is the concentration of tirzepatide dissolved in that 0.5 ml volume. This is different from other weight loss injections like Wegovy (semaglutide), which uses a different volume for each dose. Try our GLP-1 weight loss calculator to estimate potential outcomes at different tirzepatide doses.
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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.
UK Pricing & Access Routes For Mounjaro
NHS access: Mounjaro is available through NHS specialist tier 3 and tier 4 weight management services, but access varies significantly by region. You'll need a GP referral and will typically wait weeks to months for an appointment. NICE has approved tirzepatide for use within NHS weight management pathways.
Private access: Through GPhC-registered online pharmacies following an online consultation with a UK-licensed prescriber. Costs typically range from £129–£320 per month depending on dose — higher doses cost more. Private access is faster (often within days) but requires you to pay the full cost. No NHS prescription is needed for private access. Always use our BMI calculator to understand your starting point before any consultation.
NHS access: Mounjaro is available through NHS specialist tier 3 and tier 4 weight management services, but availability varies by region and integrated care board (ICB). You'll need a GP referral to a specialist weight management service, and waiting times can be substantial. NICE has approved tirzepatide (the active ingredient in Mounjaro) for use within NHS weight management pathways for eligible adults.
Private prescription route: Through GPhC-registered online pharmacies following an online clinical consultation with a UK-licensed prescriber. Private costs typically range from £129–£320 per month depending on dose (higher doses cost more). This route is usually faster — often days rather than months — but you pay the full cost. An online prescriber will assess your eligibility during 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.
Is Mounjaro cheaper on the NHS or through private prescription?
Mounjaro is free on the NHS for eligible patients, but access is limited and waiting times vary by region. Private prescription costs £129–£320/month depending on dose. NHS access requires GP referral to a specialist weight management service, whilst private access is faster but involves upfront costs.
Can I get Mounjaro prescribed by my GP directly?
No. Mounjaro is typically prescribed through NHS tier 3 specialist weight management services, not standard GP practices. For private access, you can consult with a licensed prescriber online without GP involvement. Your GP can refer you to specialist NHS services if you meet eligibility criteria.
How long does it take to get Mounjaro on prescription in the UK?
NHS access can take months or longer depending on your region and waiting lists. Private online prescription routes are typically faster — often within 3–7 days of completing your online consultation. Availability varies by ICB area for NHS access.
What happens at an online consultation for Mounjaro?
A UK-licensed prescriber will review your medical history, current medications, weight, height, and BMI. They'll assess whether tirzepatide is appropriate for you based on MHRA guidance. If approved, they'll issue a prescription that's dispensed by the online pharmacy — usually within 1–2 days.
How does Mounjaro compare to Wegovy in terms of cost and access?
Both are prescription-only in the UK. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist; Wegovy (semaglutide) is GLP-1 only. Private costs are similar (£129–£320/month). Clinical trials showed Mounjaro achieved slightly higher average weight loss (~20% vs ~15%), but individual results vary. Prescriber preference and your personal health profile will influence which is recommended.
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.