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
Mounjaro Dosing Chart — Complete UK Guide
Mounjaro (tirzepatide) is prescribed in gradually increasing doses over several months to help your body adjust and find the most effective dose for you. This UK guide explains the full dosing schedule, how the titration process works, and what happens at each stage. All Mounjaro prescriptions are prescription-only and require clinical assessment from a UK-licensed prescriber before starting. Individual response varies, and your prescriber will adjust your dose based on your progress and tolerance.
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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.
The Complete Mounjaro Dose Schedule
Mounjaro is injected once weekly, with doses starting low and increasing every 4 weeks until you reach the dose that works best for you. Here is the standard UK dosing progression:
- Weeks 1–4: 2.5 mg once weekly (starting dose)
- Weeks 5–8: 5 mg once weekly
- Weeks 9–12: 7.5 mg once weekly
- Weeks 13–16: 10 mg once weekly
- Weeks 17–20: 12.5 mg once weekly
- Week 21 onwards: 15 mg once weekly (maximum dose)
Each KwikPen contains four weeks of doses. You must stay on each dose for a minimum of 4 weeks before increasing — your prescriber will not escalate faster than this schedule. If you experience significant side effects, your dose may remain unchanged or be adjusted downward. Clinical trials showed that higher doses (10–15 mg) produced greater average weight loss, but individual response varies considerably.
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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.
Key Points About Mounjaro Dosing
Once you reach a maintenance dose that suits you (often between 7.5 mg and 15 mg), you will continue that dose weekly for as long as you and your prescriber decide to continue treatment. Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses — though individual results vary significantly. Most people experience gradual appetite reduction and feel fuller after smaller meals, particularly in weeks 4–8. If you miss a dose within 4 days, take it as soon as you remember. If more than 4 days have passed, skip that week and continue on your regular schedule. Always space doses at least 72 hours (3 days) apart.
- 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 happens if I have side effects during dose escalation?
Common side effects like nausea and stomach discomfort often improve over the first 2–4 weeks as your body adjusts. If side effects are severe, your prescriber may delay dose escalation or keep you on the same dose longer. Do not stop injecting without speaking to your prescriber — they can adjust your schedule.
Can I skip a dose or take a lower dose than prescribed?
No — always follow your prescriber's instructions exactly. If you want to change your dose, contact your prescriber first. Skipping doses or taking less will not improve tolerance and may affect your results. Your prescriber can adjust your schedule if needed.
How long does it take to reach the maximum dose?
Following the standard schedule, it takes approximately 20 weeks to reach the maximum 15 mg dose. However, not everyone escalates to 15 mg — many people find their optimal dose at 7.5 mg, 10 mg, or 12.5 mg. Your prescriber will work with you to find the dose that balances effectiveness with side effect tolerance.
What's the difference between Mounjaro and Wegovy dosing?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist starting at 2.5 mg and reaching 15 mg. Wegovy (semaglutide) is a GLP-1 agonist starting at 0.25 mg and reaching 2.4 mg. Approximate equivalence: 5 mg Mounjaro ≈ 0.5 mg Wegovy; 15 mg Mounjaro ≈ 2.4 mg Wegovy. Any switch between medications must be managed by your prescriber.
Can I use our BMI calculator and progress tracker alongside Mounjaro treatment?
Yes — our free BMI calculator helps you track how your BMI changes as weight decreases, while our progress tracker lets you log weekly weight, dose, and how you're feeling. This gives you a complete picture of your response to treatment alongside your prescriber's assessments.
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.