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 Is Mounjaro — Cost and Wegovy Comparison
Mounjaro (tirzepatide) costs vary depending on whether you access it through the NHS or privately in the UK. On the NHS, it's free at the point of use if prescribed through specialist tier 3 weight management services. Privately, the cost typically ranges from £129 to £320 per month depending on your dose. Wegovy (semaglutide) has similar private pricing. Both are prescription-only medications requiring a clinical assessment before being prescribed. Understanding the costs and how they compare helps you make an informed decision with your healthcare provider.
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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 vs Wegovy — Cost, Doses, and Trial Results
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist manufactured by Eli Lilly. Private costs typically range from £129–£320 per month depending on dose strength (starting at 2.5 mg, rising to a maximum of 15 mg weekly). On the NHS, tirzepatide is covered at no charge if prescribed through specialist weight management services, though access and waiting times vary significantly by region and ICB.
Wegovy (semaglutide) is a single GLP-1 receptor agonist made by Novo Nordisk. Private costs are broadly similar, ranging from around £150–£300 per month. It uses a lower maximum dose (2.4 mg weekly) compared to Mounjaro's 15 mg. Both require four-week titration periods between dose increases, meaning early costs reflect lower doses than maintenance doses.
- Trial data: SURMOUNT-1 (Mounjaro) showed average weight loss of 15–21% body weight; STEP-1 (Wegovy) showed approximately 14.9% at maximum dose.
- Mechanism: Mounjaro's dual action (GIP + GLP-1) differs from Wegovy's single GLP-1 pathway, though both medications help reduce appetite and support weight loss alongside diet and exercise.
Clinically BackedWeight Loss
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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.
Which Is Right for You — Individual Suitability
Neither Mounjaro nor Wegovy is universally "better" — suitability depends on your individual health profile, medical history, and how your body responds. A prescriber will assess your eligibility based on BMI (30 or above, or 27+ with weight-related health conditions like type 2 diabetes or hypertension) and any contraindications. Both medications are prescription-only and require a clinical assessment before being prescribed, whether through NHS specialist services or private online prescribing.
Cost, availability, and personal preference all play a role in your choice. The NHS may prescribe either tirzepatide or semaglutide depending on local formulary and current NICE guidance. Privately, you can discuss both options with a licensed UK prescriber. Remember that both medications work best alongside a reduced-calorie diet and increased physical activity — use our GLP-1 weight loss calculator to estimate potential results with either medication, and try our BMI calculator to check your starting point.
- 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.
How much does Mounjaro cost privately in the UK?
Private Mounjaro typically costs £129–£320 per month depending on dose strength. Starting doses (2.5–5 mg) are at the lower end; maximum doses (10–15 mg) are at the higher end. Costs vary between private prescribing services and UK pharmacies. Always confirm the exact price with your pharmacy before ordering.
Is Mounjaro cheaper than Wegovy in the UK?
Private costs are broadly similar, ranging £129–£320 monthly for both. Wegovy costs are typically £150–£300 per month. The difference may be £10–£50 depending on your dose and provider. NHS access is free for both, though availability and waiting times vary by region. Cost alone should not determine your choice — suitability is more important.
Can I get Mounjaro on the NHS in the UK?
Yes, tirzepatide (Mounjaro) is NICE-approved for NHS use in specialist tier 3 weight management services. However, NHS access varies significantly by region, and waiting lists can be lengthy (months to years in some areas). Eligibility requires referral from your GP and assessment by specialist services. Private access bypasses NHS waiting lists entirely.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) activates two pathways — GIP and GLP-1; Wegovy (semaglutide) activates GLP-1 only. Mounjaro's maximum dose is 15 mg weekly; Wegovy's is 2.4 mg weekly. Clinical trials showed Mounjaro produced slightly higher average weight loss (15–21% vs ~15%), though individual results vary significantly. Both require prescription and clinical assessment.
Do I need to pay for Mounjaro if it's prescribed by the NHS?
No — if Mounjaro (tirzepatide) is prescribed through the NHS, it's free at the point of use (you pay standard prescription charges if applicable, unless you're exempt). Privately prescribed Mounjaro costs £129–£320 per month. Always ask your GP about NHS eligibility first, as waiting lists vary by area and some regions may have limited access.
Ready to take control of your weight loss journey?
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