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
What Is the Mounjaro Dose Range in the UK?
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK that uses a gradual dose titration schedule. Starting at 2.5 mg per week, the dose gradually increases over several weeks if needed, up to a maximum of 15 mg per week. Each dose is a once-weekly injection administered using a pre-filled KwikPen device. Your prescriber will assess your individual response and health needs to determine the right dose for you, as individual results vary significantly. Always follow your prescriber's guidance on dose timing and adjustments.
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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 Schedule and Titration
Mounjaro follows a structured dose titration schedule, meaning your dose gradually increases every 4 weeks if you're tolerating the medication well. Starting at 2.5 mg per week for the first month, the dose steps up to 5 mg, then 7.5 mg, 10 mg, 12.5 mg, and finally 15 mg (the maximum dose). Each increase is separated by at least 4 weeks on the previous dose. This gradual approach allows your body to adjust to the medication and minimises nausea and digestive side effects. Your GP or prescriber may keep you at a lower dose if that's working effectively for you — you don't automatically progress to 15 mg. Each KwikPen contains 4 weekly doses (one month's supply), delivered as a single injection each week on the same day.
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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.
How Your Prescriber Decides Your Mounjaro Dose
Your prescriber will personalise your Mounjaro dosing based on several factors: your starting weight and BMI, your response to the medication, any side effects you experience, and your overall health status. Calculate your personal BMI using our free BMI calculator to understand your starting point. If you experience significant nausea or other side effects, your prescriber may slow the dose increase or keep you at a lower effective dose longer. Some patients achieve their weight loss goals at 5 mg or 10 mg and don't progress further — there's no "one size fits all" approach. Always report side effects to your prescriber; they can adjust your dosing plan accordingly. Individual tolerance and outcomes vary considerably.
- 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 is the starting dose of Mounjaro?
The starting dose is 2.5 mg once per week. This is taken for the first 4 weeks to allow your body to adjust. Your prescriber will then increase the dose by steps of 2.5 mg every 4 weeks if you're tolerating it well and your clinical response is appropriate.
What is the maximum Mounjaro dose in the UK?
The maximum approved dose is 15 mg once per week. You don't automatically reach this dose — your prescriber personalises your dosing based on your response, side effects, and health needs. Some patients achieve good results at lower doses.
How often do I increase my Mounjaro dose?
Doses increase every 4 weeks minimum if you're progressing through the titration schedule. Your prescriber may slow this if you experience side effects or keep you at a dose that's working well for you.
Can I skip a dose increase if I'm happy with my current weight loss?
Yes. There's no requirement to reach the maximum dose. If you're achieving good results at 5 mg, 10 mg, or any other dose, your prescriber may recommend staying at that level rather than continuing to escalate.
What should I do if I miss a Mounjaro injection?
If you miss a dose within 4 days of when you should have taken it, take it as soon as you remember and continue your normal weekly schedule. If it's more than 4 days late, skip that dose and resume your regular schedule the following week.
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.