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 A Dose Of Mounjaro?
Mounjaro comes in doses ranging from 2.5 mg to 15 mg, with each dose delivered as a once-weekly injection using a pre-filled KwikPen device. The amount you inject depends on where you are in your treatment plan — you'll start at a lower dose and gradually increase over several weeks. Your prescriber will determine the right dose for you following a clinical assessment. Understanding the dose schedule helps you know what to expect when you begin treatment or progress through your titration plan.
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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 Schedule and Titration
Mounjaro uses a gradual titration approach, meaning you start at a low dose and increase every 4 weeks if needed. Each dose is injected once weekly using the pre-filled KwikPen device, with each pen containing 4 weekly doses. The standard dose progression is: Week 1–4: 2.5 mg (starting dose); Week 5–8: 5 mg (first escalation); Week 9–12: 7.5 mg (if needed); Week 13–16: 10 mg (if needed); Week 17–20: 12.5 mg (if needed); Week 21+: 15 mg (maximum maintenance dose). Most people remain on a maintenance dose between 5 mg and 15 mg. You cannot skip doses or take a double dose — the minimum time between injections is 7 days (approximately weekly). Your prescriber may adjust your schedule based on how you respond and any side effects you experience.
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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 Each Mounjaro Dose Means
Each dose step represents an increase in the tirzepatide concentration in your injection. The 2.5 mg starting dose allows your body to adjust to how the medication works, reducing initial side effects like nausea. Once your body has adapted over 4 weeks, escalating to 5 mg or higher typically produces stronger appetite-suppressing effects. Clinical trials showed that higher doses (10 mg and 15 mg) were associated with greater average weight loss, though individual results vary significantly. Some people find their optimal dose at 5 mg or 7.5 mg and don't need to escalate further — this is normal and depends on your personal response. Never increase your dose without guidance from your prescriber. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses based on clinical trial data.
- 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 weekly. This is a lower dose designed to allow your body to adjust to the medication and reduce initial side effects like nausea. After 4 weeks, your prescriber may increase you to 5 mg if appropriate.
How much does each Mounjaro KwikPen contain?
Each pre-filled KwikPen contains 4 weekly doses at the same concentration. For example, a 5 mg pen contains four 5 mg injections — enough for 4 weeks of treatment. You'll need a new pen each month.
What is the maximum Mounjaro dose in the UK?
The maximum dose is 15 mg once weekly. Most people reach an effective dose between 5 mg and 10 mg, but some may benefit from the higher 15 mg dose. Your prescriber will assess what's right for you.
How quickly does Mounjaro dose increase?
Mounjaro follows a titration schedule with a minimum of 4 weeks at each dose before increasing. You cannot escalate faster than once every 4 weeks. If you experience side effects, your prescriber may keep you on the same dose longer or reduce it.
What happens if I miss a Mounjaro injection?
If you miss a dose by 4 days or less, inject it as soon as you remember and continue your normal schedule. If more than 4 days have passed, skip that dose and take your next injection on your regular day. Never take two doses close together.
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.