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
How Much Is The Weight Loss Injection in the UK?
Weight loss injections like Mounjaro and Wegovy typically cost between £129 and £320 per month in the UK, but the real answer depends on your personal health profile. Eligibility isn't just about price — it's about whether the medication is appropriate for you based on your BMI, health conditions, and individual circumstances. Your ideal weight for your height is the starting point for understanding whether prescription weight loss treatment might be suitable, and our free BMI calculator can help you assess this in seconds.
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.
Understanding Your BMI and Eligibility
Weight loss injections are prescription-only medicines available in the UK through NHS specialist services or private prescribing following a clinical assessment. The cost varies depending on the dose and supplier, but understanding your healthy weight range is crucial first.
UK eligibility criteria:
- BMI of 30 kg/m² or above (obesity), OR
- BMI of 27–29.9 kg/m² with weight-related health conditions (type 2 diabetes, high blood pressure, sleep apnoea)
- For South Asian, Chinese, Black African, or Black Caribbean adults: BMI 27.5 or above may qualify
Use our free BMI calculator above to check where you fall. A healthy weight for your height according to NHS guidelines is a BMI between 18.5 and 24.9. If your BMI is above this range, your GP can discuss whether prescription treatment or lifestyle changes are the right next step for you.
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.
What to Do If You're Above Your Healthy Weight
If the BMI calculator shows you're above the healthy weight range, you have several options. First, speak to your GP about your individual situation — they can assess your health holistically and discuss whether weight loss injections, lifestyle support, or the NHS weight management pathway is most appropriate for you. You can also calculate your ideal weight range using our free weight converter and BMI tools to see what a healthy weight looks like in stone, lbs, or kg for your height.
The NHS also offers free support through weight management services (tier 1–4), accessible through your GP. Private prescribing is available without NHS referral but requires a consultation with a UK-licensed prescriber to ensure the medication is safe for you.
- 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 do weight loss injections cost in the UK?
Private weight loss injections (Mounjaro or Wegovy) typically cost £129–£320 per month depending on dose and provider. Starting doses are lower and cost less. NHS access is through specialist services and is free at point of use, though waiting times vary significantly by region.
What BMI do I need to qualify for weight loss injections?
Generally, a BMI of 30 or above qualifies. If your BMI is 27–29.9, you may be eligible if you have weight-related health conditions like type 2 diabetes or high blood pressure. Use our BMI calculator to check yours, then discuss eligibility with your GP or a prescriber.
Is my current weight healthy for my height?
Your ideal weight depends on your height and individual health. A healthy BMI is 18.5–24.9 according to NHS guidelines. Our free BMI calculator tells you instantly whether your current weight falls in the healthy range for your specific height and age.
Can I access weight loss injections through the NHS?
Yes, but through specialist tier 3 weight management services, not routine GP prescription. You'll need a referral from your GP. Availability and waiting times vary significantly by region (ICB). Private access is faster but costs £129–£320 per month.
What's the difference between my ideal weight and needing a weight loss injection?
Your ideal weight is your personal healthy weight range based on your height and BMI. Weight loss injections are prescribed when lifestyle changes alone haven't worked and your BMI is 30+ (or 27+ with health conditions). A prescriber will assess whether injections are appropriate after clinical assessment.
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.