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 Much Is 2.5 Mg Mounjaro In Ml?
The 2.5 mg starter dose of Mounjaro (tirzepatide) is delivered as a pre-filled KwikPen injection containing approximately 0.25 ml of solution. This is the standard starting dose prescribed in the UK for adults beginning weight management treatment with tirzepatide. Each KwikPen contains four weekly doses, so a single pen supplies four weeks of treatment. Understanding the volume helps you recognise what to expect when your prescription arrives. Use our free GLP-1 weight loss calculator above to explore how Mounjaro might support your weight management goals at different dose levels.
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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 2.5 Mg Dosing And NHS Eligibility In The UK
The 2.5 mg dose is always the starting point for Mounjaro in the UK, regardless of whether you're accessing treatment through NHS specialist services or private prescription. This starter dose is injected once weekly, and each KwikPen pen contains four doses (one month's supply). After 4 weeks at 2.5 mg, your prescriber will typically increase you to 5 mg, then to higher doses over subsequent weeks if clinically appropriate, up to a maximum of 15 mg weekly.
NHS eligibility for Mounjaro requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions including type 2 diabetes, high blood pressure, or cardiovascular disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify with lower BMI thresholds. Access is through NHS tier 3 specialist weight management services following referral from your GP. NICE has approved tirzepatide for use within NHS services, though regional availability varies significantly. Check with your local Integrated Care Board (ICB) for specific access routes in your area.
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 Versus Private Routes For Mounjaro In The UK
NHS route: Referral to your local tier 3 specialist weight management service, clinical assessment, then prescription through the NHS. This route is free but involves waiting lists that can be substantial in many regions. Your GP can advise on local waiting times and referral criteria.
Private route: Online consultation with a UK-licensed prescriber, assessment, and dispensing through a GPhC-registered pharmacy if suitable. Available without NHS referral and typically faster access, though costs apply (usually £129–£200+ per month depending on dose). Both routes require a genuine clinical assessment before any dose, including the 2.5 mg starter dose. Track your weight progress using our free progress tracker to monitor results alongside treatment.
- 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 the 2.5 mg Mounjaro dose safe as a starter?
Yes. The 2.5 mg dose is the approved and standard starting dose in the UK for all adults beginning Mounjaro treatment. It allows your body to adjust to the medication before dose escalation. Your prescriber will monitor how you respond before increasing to 5 mg after 4 weeks.
How long do you stay on 2.5 mg Mounjaro?
Typically 4 weeks. After the initial 4-week period on 2.5 mg, your prescriber will usually increase your dose to 5 mg if tolerated. Dose increases happen every 4 weeks until you reach an effective maintenance dose or the maximum of 15 mg.
Can I skip the 2.5 mg starter dose and start on a higher dose?
No. UK prescribing guidelines require starting at 2.5 mg regardless of your BMI or health status. Starting higher carries greater risk of side effects like nausea and vomiting. The gradual escalation approach is supported by clinical evidence and MHRA approval.
What's the difference between Mounjaro and Wegovy starting doses?
Mounjaro starts at 2.5 mg once weekly. Wegovy starts at 0.25 mg once weekly. Although Mounjaro is a different medication (dual GIP and GLP-1 agonist versus GLP-1 only), both follow a gradual dose-escalation schedule. Clinical trials showed different average weight loss outcomes at maximum doses.
Can I get Mounjaro on NHS without seeing a specialist first?
No. Mounjaro is only prescribed through NHS tier 3 specialist weight management services after GP referral and specialist assessment. You cannot obtain it as a standard GP prescription. Private routes offer faster access if you prefer to avoid NHS waiting lists.
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.