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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Mounjaro Dosage Chart In ML — NHS Prescribing Guide
Mounjaro (tirzepatide) is prescribed in the UK as a once-weekly injection, with doses measured in milligrams rather than millilitres. The dosage chart starts at 2.5 mg and escalates gradually over 16 weeks to a maximum of 15 mg, with each step spaced four weeks apart. This guide explains the full NHS and UK prescribing schedule, eligibility criteria through NICE guidance, and how the Mounjaro KwikPen delivers each dose. Understanding the dosage progression helps you know what to expect if prescribed by your GP or a specialist weight management service.
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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 Dosage Chart — Complete Titration Schedule
Mounjaro is dosed in milligrams (mg), not millilitres (ml). Each pre-filled KwikPen contains enough medication for four weekly injections. The standard UK titration schedule is:
- Weeks 1–4: 2.5 mg once weekly (starting/adjustment 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+: 15 mg once weekly (maximum maintenance dose)
Your prescriber may adjust this schedule based on tolerability and response. Minimum time between dose increases is four weeks. Some patients remain on lower doses if they experience side effects or achieve their weight loss goals earlier. The GLP-1 weight loss calculator on this page can help you estimate potential outcomes at different doses based on clinical trial data.
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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.
NHS Eligibility and UK Prescribing Routes
In the UK, Mounjaro (tirzepatide) is available through two routes: NHS specialist services and private prescribing. NHS access is through tier 3 weight management services following GP referral — NICE has approved tirzepatide for adults with BMI ≥30, or BMI 27–29.9 with weight-related health conditions including type 2 diabetes, hypertension, or cardiovascular disease. South Asian, Black African, Black Caribbean, and Chinese adults may qualify at lower BMI thresholds. Private prescribing is available through registered online services following a clinical assessment. Waiting times for NHS services vary significantly by region; some areas have year-long lists. Use our free BMI calculator to check your starting point and eligibility bracket.
- 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's the difference between Mounjaro dosage in mg and ml?
Mounjaro is measured in milligrams (mg) of active ingredient tirzepatide, not millilitres (ml) of liquid. The KwikPen automatically delivers the correct dose when you inject — you don't measure ml yourself. Each pen contains four weekly doses and is clearly labelled with the mg strength.
How long does it take to reach the maximum 15 mg dose?
Following the standard titration schedule, it takes 20 weeks (approximately five months) to reach the maximum 15 mg dose. Your prescriber may adjust this timeline based on how you tolerate each dose and your individual response. Some patients stay on lower doses if they're achieving good results.
Can you stay on a lower Mounjaro dose than 15 mg?
Yes. Many patients maintain on 5 mg, 10 mg, or 12.5 mg if they experience significant weight loss, side effect management, or good metabolic results. Your prescriber will assess whether continuing to escalate is appropriate for you based on your health goals and tolerance.
Is Mounjaro available on the NHS in all UK regions?
No. NHS access varies significantly by region and ICB (integrated care board). Some areas have well-established tier 3 weight management services; others have long waiting lists or limited capacity. Contact your GP to check availability in your area or explore private prescribing options.
How does Mounjaro dosing compare to Wegovy?
Mounjaro is a dual GIP/GLP-1 agonist (doses 2.5–15 mg), while Wegovy (semaglutide) is a GLP-1 agonist only (doses 0.25–2.4 mg). They use different dosing schedules and mechanisms, so doses aren't directly comparable. Your prescriber will recommend whichever is most appropriate for your individual needs.
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.