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
What Is the Mounjaro Equivalent to 1mg Wegovy?
Comparing Wegovy and Mounjaro dosages directly is not straightforward because they work differently. Wegovy (semaglutide) is a GLP-1 receptor agonist, while Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist. Approximate clinical equivalence suggests that Wegovy 1mg is roughly comparable to Mounjaro 5mg in terms of weight loss effect, though individual results vary significantly. Both are prescription-only medicines requiring clinical assessment in the UK, and prescribers choose between them based on your personal health profile, not dose alone.
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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.
NHS Prescribing, NICE Guidance, and UK Eligibility
Both Wegovy and Mounjaro are approved by the MHRA and NICE for weight management in UK adults. NHS prescribing follows NICE guidance and is available through specialist tier 3 weight management services, not standard GP prescription. Eligibility criteria include:
- BMI of 30 kg/m² or above, or
- BMI of 27–29.9 kg/m² with weight-related health conditions (type 2 diabetes, hypertension, cardiovascular disease, sleep apnoea)
- Lower thresholds apply for adults of South Asian, Chinese, Black African, or Black Caribbean heritage (BMI 27.5+)
In clinical trials, Wegovy at 1mg achieved modest weight loss, with the maximum dose (2.4mg) showing average weight loss of approximately 15% of body weight over 68 weeks alongside reduced-calorie diet and increased activity. Individual responses to tirzepatide (Mounjaro) via the SURMOUNT trial showed 15–21% average weight loss across doses. Both require ongoing clinical monitoring through NHS or private services.
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.
NHS vs Private Access Routes for Wegovy in the UK
Accessing Wegovy through the NHS involves referral to a specialist weight management service by your GP, which can involve significant waiting times in many regions. Private prescribing offers faster access through UK-licensed prescribers following an online clinical assessment and is dispensed by GPhC-registered pharmacies. Private costs range from approximately £129–£280 per month depending on dose. Your GP can advise whether NHS tier 3 services are available in your area. Use our free GLP-1 weight loss calculator to explore potential outcomes at different Wegovy doses, and our BMI calculator to understand your current health category and eligibility. Both tools are available on this page.
- 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 approximate Mounjaro equivalent to Wegovy 1mg?
Wegovy 1mg is approximately equivalent to Mounjaro 5mg in clinical effect, though these are estimates based on clinical practice guidance — there is no official conversion chart. Both drugs work via different mechanisms (semaglutide vs tirzepatide), so direct equivalence is not precise. Your prescriber will choose the most appropriate medication for your individual health profile, not based on dose alone.
Can I switch from Wegovy to Mounjaro on the NHS?
Switching between weight loss medications on the NHS requires referral to a specialist weight management service and prescriber assessment. NHS availability varies significantly by region and ICB (Integrated Care Board). Private prescribers can assess suitability for either medication following an online consultation, offering faster access than NHS waiting lists in many areas.
Does NICE recommend Wegovy or Mounjaro?
NICE has approved both Wegovy (semaglutide) and Mounjaro (tirzepatide) for use in NHS specialist tier 3 weight management services. NICE does not recommend one over the other — prescribers select based on individual patient factors, clinical suitability, and local service availability. Both carry the same NHS eligibility criteria.
Is Wegovy available through my GP or specialist referral?
Wegovy is not available through standard GP prescription in the UK. Access is through NHS specialist tier 3 weight management services following GP referral. Alternatively, private prescribing is available without NHS referral through online UK-licensed prescribers. Ask your GP whether tier 3 services are commissioned in your local area.
What does the STEP trial tell us about Wegovy 1mg effectiveness?
The STEP-1 clinical trial showed that Wegovy achieved average weight loss of approximately 14.9% of body weight at the maximum dose (2.4mg) over 68 weeks. At 1mg (an early escalation dose), weight loss was more modest. Results were achieved alongside a reduced-calorie diet and increased physical activity. Individual results vary based on genetics, adherence, lifestyle changes, and other health factors.
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.