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
Wegovy vs Mounjaro Dosage — UK Access and Cost Guide
Wegovy and Mounjaro are both prescription-only weight management injections available in the UK, but they work differently and cost differently depending on whether you access them through the NHS or privately. This guide explains the dosing differences, cost context, and how to access each medication in the UK. Use our free GLP-1 weight loss calculator above to understand potential outcomes at different doses, and our BMI calculator to check your eligibility baseline.
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.
Dosage Differences and NHS vs Private Access
Wegovy (semaglutide) is a once-weekly GLP-1 receptor agonist that starts at 0.25 mg and escalates gradually to a maximum of 2.4 mg over approximately 16 weeks. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist starting at 2.5 mg and escalating to a maximum of 15 mg over several months — making it a different molecule with a distinct mechanism. In clinical trials, Mounjaro showed slightly higher average weight loss than Wegovy, though individual results vary significantly.
- Wegovy: 0.25 mg → 0.5 mg → 1 mg → 1.7 mg → 2.4 mg (final dose)
- Mounjaro KwikPen: 2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mg (final dose)
- Both require minimum 4 weeks at each dose before escalation
NHS access to either medication is through specialist tier 3 weight management services via GP referral. Private access is faster — available through UK-licensed online prescribers without an NHS referral, though costs and availability vary by provider. A mounjaro UK prescription through private channels typically costs £129–£320 per month depending on dose; Wegovy private prescription pricing is similar.
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.
How to Access Wegovy or Mounjaro in the UK
NHS route: Ask your GP for a referral to your local tier 3 specialist weight management service. Eligibility requires BMI ≥30, or BMI 27–29.9 with weight-related health conditions (high blood pressure, type 2 diabetes, sleep apnoea). Assessment timescales vary significantly by region — some services have waiting lists of 6–12 months or longer.
Private route: Complete an online consultation with a UK-licensed prescriber. Answer questions about medical history, current medications, and weight goals. If approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. Costs are per-dose and billed monthly. First consultations typically cost £30–£50, with prescription costs on top.
Track your weight loss progress using our free progress tracker once you start medication.
- 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.
Is Mounjaro or Wegovy cheaper on the NHS?
Both are available through NHS specialist services, but neither is routinely available through standard GP prescription. NHS availability depends on your local tier 3 service and current NICE guidance. Private costs are broadly similar (£129–£320/month), though exact pricing varies by dose and provider.
What's the main difference between Mounjaro and Wegovy dosing?
Wegovy starts at 0.25 mg and reaches 2.4 mg maximum; Mounjaro starts at 2.5 mg and reaches 15 mg maximum. Mounjaro is a dual GIP + GLP-1 agonist (different mechanism), while Wegovy is GLP-1 only. Clinical trials showed Mounjaro may produce slightly higher average weight loss, though results vary individually.
How long does it take to reach the maximum dose?
Wegovy takes approximately 16 weeks to reach 2.4 mg (four weekly escalations). Mounjaro typically takes 20+ weeks to reach 15 mg (six or more escalations). Both require a minimum of 4 weeks at each dose before increasing, and prescribers may adjust timelines based on your response and tolerability.
Can I switch from Wegovy to Mounjaro or vice versa?
Switching between medications is possible but must be managed by your prescriber. There is no official standard conversion between doses — your prescriber will assess your current response and adjust accordingly. Mounjaro's dual mechanism means direct equivalence cannot be established, so individual assessment is essential.
What happens after I reach maximum dose?
Once you're on a maintenance dose (2.4 mg for Wegovy or your effective Mounjaro dose), you continue that dose as long as it's effective and well tolerated. If you stop medication, weight regain typically occurs over weeks to months. Many people stay on treatment long-term if it's working; others may pause or stop with their prescriber's guidance.
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.