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 Mounjaro — UK Doses and Costs Explained
Mounjaro (tirzepatide) comes in doses ranging from 2.5 mg to 15 mg as a once-weekly injection in the UK. The amount you receive depends on your individual response and how well you tolerate the medication — your prescriber will start you on the lowest dose and gradually increase it over weeks. Private costs typically range from £150 to £300 per month depending on your dose, whilst NHS access requires referral to specialist weight management services. Understanding the dose range and what to expect can help you prepare for treatment.
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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 is prescribed in a step-wise titration schedule, meaning you start low and gradually increase:
- 2.5 mg — weeks 1–4 (starting dose)
- 5 mg — weeks 5–8 (first maintenance)
- 7.5 mg — weeks 9–12 (if needed)
- 10 mg — weeks 13–16 (if needed)
- 12.5 mg — weeks 17–20 (if needed)
- 15 mg — week 21+ (maximum dose)
Each dose is a once-weekly KwikPen injection. You must stay on each dose for at least 4 weeks before increasing — this gives your body time to adapt and allows your prescriber to assess how well you're tolerating it. Not everyone reaches the maximum dose; many people achieve their weight loss goals at 5 mg or 10 mg. Your prescriber will decide the right dose for you based on your progress 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.
Cost, Availability, and What to Expect
Private costs: Mounjaro typically costs £150–£300 per month depending on dose and provider in the UK. A standard 4-week supply (one KwikPen containing 4 injections) is usually £150–£200 at lower doses, rising to £250–£300 at higher doses. NHS access: Available through specialist tier 3 weight management services following GP referral, though availability and waiting times vary significantly by region. Clinical trials showed that patients on 15 mg Mounjaro lost an average of approximately 21% of their body weight over 72 weeks — though individual results vary considerably. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses.
- 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 in the UK?
The starting dose is 2.5 mg, given as a once-weekly injection. You stay on this dose for 4 weeks before your prescriber may increase it. This allows your body to adjust and helps monitor for side effects.
Can I go straight to the highest Mounjaro dose?
No. Mounjaro must be titrated gradually — you cannot start on 15 mg. The step-wise schedule (2.5 mg → 5 mg → 7.5 mg, etc.) reduces nausea and other side effects. Each dose increase happens after a minimum of 4 weeks.
How much does a Mounjaro KwikPen cost in the UK?
A standard KwikPen (4 weeks supply) costs approximately £150–£200 at lower doses (2.5–5 mg) and £250–£300 at higher doses (10–15 mg). Prices vary between private providers. NHS prescriptions are free to eligible patients.
Will I need to stay on Mounjaro forever?
This depends on your individual goals and prescriber's advice. Some people continue long-term to maintain weight loss; others stop after reaching their target. Weight often returns if treatment stops, so your prescriber will discuss the best approach for you.
How does Mounjaro dose compare to Wegovy dose?
Mounjaro and Wegovy use different measurements — approximate equivalence is: Mounjaro 5 mg ≈ Wegovy 0.5 mg, Mounjaro 10 mg ≈ Wegovy 1.7 mg, and Mounjaro 15 mg ≈ Wegovy 2.4 mg. However, only your prescriber should manage any medication switch. Try our BMI calculator to check your eligibility for either medication.
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.