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 Much Is In Mounjaro — UK Dose Breakdown
Mounjaro (tirzepatide) comes in five different doses, ranging from 2.5 mg to 15 mg, with each KwikPen containing four weekly doses. The exact amount of medication in your Mounjaro injection depends on which dose your prescriber has determined is right for you following your initial assessment. This guide explains the full dosing schedule, how doses are titrated (increased), and what each dose typically contains. Understanding your Mounjaro dose helps you manage your prescription effectively and track your progress alongside our free GLP-1 weight loss calculator.
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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 Dose Range and Titration Schedule
Mounjaro comes in five prescribable doses as part of a structured dose titration schedule. Each dose is a once-weekly injection delivered via a pre-filled KwikPen device:
- 2.5 mg — starting dose (weeks 1–4)
- 5 mg — first escalation dose (weeks 5–8)
- 7.5 mg — second escalation dose (weeks 9–12)
- 10 mg — third escalation dose (weeks 13–16)
- 12.5 mg — fourth escalation dose (weeks 17–20)
- 15 mg — maximum maintenance dose (week 21 onwards)
Most people start at 2.5 mg and remain on each dose for a minimum of four weeks before increasing. Your GP or prescriber will decide whether to increase your dose based on your individual response, tolerability, and how well you are managing any side effects. Each KwikPen contains enough medication for four weekly injections, so one pen supplies one month of treatment at a fixed dose.
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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.
What to Expect at Each Mounjaro Dose
Clinical trials showed that higher Mounjaro doses were associated with greater average weight loss — approximately clinically studied weight loss at 5 mg, rising to around 21% at the maximum 15 mg dose. However, individual results vary significantly, and some people achieve meaningful weight loss at lower doses like 5 mg or 7.5 mg. Many people find that staying at a mid-range dose (7.5–10 mg) gives them good results with manageable side effects. Common side effects like nausea often improve over time as your body adjusts. Your prescriber will monitor your progress and discuss whether dose escalation is right for you. Use our free BMI calculator to track changes in your BMI as your treatment progresses, and consider our progress tracker to log your weight loss journey week by week.
- 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.
What dose of Mounjaro should I start on?
Everyone starts on 2.5 mg as the initial dose, regardless of their eventual target dose. This allows your body to adjust to the medication and helps minimise nausea and other side effects. You remain on 2.5 mg for four weeks before your prescriber considers increasing to 5 mg.
How often do I increase my Mounjaro dose?
Doses are typically increased every four weeks if you are tolerating the medication well and your prescriber agrees escalation is appropriate. You must stay on each dose for a minimum of four weeks before moving to the next one. Not everyone needs to reach the maximum 15 mg dose.
Is 15 mg the maximum Mounjaro dose available in the UK?
Yes, 15 mg is the highest licensed dose of Mounjaro for weight management in the UK. Clinical trials showed this dose produced the greatest average weight loss, but lower doses may be equally effective for you individually.
Can I stay on 5 mg or 7.5 mg Mounjaro long-term?
Yes, absolutely. You do not need to reach the maximum dose to benefit from Mounjaro. Many people remain on mid-range doses like 5 mg, 7.5 mg, or 10 mg if they are experiencing good results with manageable side effects. Your prescriber will help you find the right dose for you.
How much tirzepatide is in each KwikPen?
Each Mounjaro KwikPen contains enough medication for exactly four once-weekly injections at the specified dose. For example, a 5 mg pen contains 20 mg total tirzepatide (4 injections × 5 mg each). Every pen must be disposed of 30 days after first use, even if unused doses remain.
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.