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
Getting Mounjaro: Your GP and UK Prescription Options
If you're considering Mounjaro (tirzepatide) for weight management, you'll need a prescription from a UK-licensed prescriber. Access in the UK works in two main routes: through the NHS via your GP and specialist weight management services, or privately through an online clinical assessment. Understanding your options, costs, and eligibility can help you make an informed decision about whether this prescription-only injection is right for you.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
How Much Does Mounjaro Cost in the UK?
Private costs for Mounjaro in the UK typically range from £129 to £320 per month, depending on your dose and the provider. Prices vary because different GPhC-registered online pharmacies set their own fees. The 2.5 mg starting dose is usually the cheapest option, while the 15 mg maximum dose is the most expensive. Each Mounjaro KwikPen contains four weekly injections, so monthly costs assume a four-week supply. Some private providers offer package deals or repeat prescription discounts. NHS costs are free at point of use if your GP refers you to a tier 3 specialist weight management service, though access depends on your local ICB (Integrated Care Board) and can involve lengthy waiting lists in many areas. Your GP can provide accurate pricing for your specific dose if accessing privately.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 vs Private: Which Route Is Right for You?
NHS route: Your GP refers you to a specialist tier 3 or tier 4 weight management service, where a multidisciplinary team assesses you. If approved, Mounjaro is prescribed free. Waiting lists can be months or even years depending on your region. Private route: You complete an online clinical assessment with a UK-licensed prescriber, usually within 24 hours. If approved, a prescription is sent to a GPhC-registered pharmacy and delivered to your address. No GP referral needed. Faster access but you pay for the medication. Both routes require eligibility assessment — you'll need a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure. Use our free BMI calculator above to check your BMI and help with your discussion with a healthcare professional.
- 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.
Can my GP prescribe Mounjaro directly?
Your GP cannot prescribe Mounjaro directly on the NHS. You must be referred to a specialist tier 3 weight management service through your GP. They will then assess your eligibility and manage your prescription. Private prescribers can issue prescriptions without NHS referral following an online assessment.
How long does it take to get Mounjaro privately?
Private access is usually faster. You complete an online clinical assessment, typically get a prescriber decision within 24 hours, and receive your Mounjaro KwikPen by post within 2–5 working days. NHS routes can take months due to waiting lists.
What dose should I start on?
All users start on 2.5 mg weekly, regardless of route (NHS or private). Your prescriber increases the dose every 4 weeks if needed and tolerated, titrating up to 15 mg. Dose titration is personalised — some people stay on lower doses, others reach the maximum.
What if I can't afford private Mounjaro?
Explore NHS referral through your GP for free access, though waiting times vary by region. Some private providers offer payment plans or reduced fees. Alternatively, discuss other weight management options with your GP, including lifestyle programmes or other treatments.
Do I need a GP to access Mounjaro on the NHS?
Yes, you need your GP to make the referral to specialist weight management services. If you're accessing privately, you don't need GP involvement — you go directly through a private online prescriber. Either way, inform your GP about any weight loss medication you're taking.
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.