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 Does the Weight Loss Injection Cost in the UK?
Weight loss injections such as Mounjaro and Wegovy cost between £129 and £320 per month through private providers in the UK, depending on dose and supplier. NHS access is free through specialist services, but availability varies significantly by region and waiting times can be lengthy. Before considering cost, it's important to understand if you're eligible — use our free BMI calculator to check your personal BMI, which is a key factor in eligibility assessment for these medications.
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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.
Understanding Your BMI and Eligibility for Weight Loss Treatment
Weight loss injections are prescription-only medications that require a clinical assessment before they can be prescribed. Your BMI (body mass index) is the primary eligibility criterion. According to NHS guidelines, you may qualify for prescription weight loss treatment if you have a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply — eligibility may start at BMI 27.5 or above. Use our free BMI calculator on this page to determine your current BMI and understand where you fall on the NHS healthy weight range. This will give you a clearer picture of your eligibility status and what your ideal weight for your height might be.
Remember that BMI is a screening tool with limitations — it doesn't account for muscle mass or where fat is stored. Your GP or a prescriber will assess your individual situation during a clinical consultation.
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 Cost and What Affects Your Price
NHS access: Free through specialist tier 3 weight management services, but requires referral from your GP. Availability and waiting times vary significantly by region — some areas have waiting lists of several months or longer.
Private access: Costs range from approximately £129–£320 per month, depending on the medication, dose, and provider. Higher doses cost more — for example, Mounjaro 2.5 mg (starting dose) typically costs less than Mounjaro 15 mg (maximum dose). Once you start treatment, the cost per month remains consistent for your chosen dose.
Many people use our GLP-1 weight loss calculator to estimate potential outcomes at different doses before committing financially. This can help you weigh the cost against realistic expectations for your situation.
- 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 weight loss injections are available in the UK?
The main options are Mounjaro (tirzepatide), Wegovy (semaglutide 2.4 mg), and Saxenda (liraglutide). Mounjaro and Wegovy are once-weekly injections; Saxenda is a daily injection. All are prescription-only and require a clinical assessment to determine suitability.
Can I get weight loss injections through the NHS for free?
Yes, they're free through NHS specialist weight management services (tier 3), but you need a GP referral and availability varies by region. Many areas have long waiting lists. Private prescription is an alternative if you prefer faster access.
Does my BMI affect whether I can get the injection?
Yes, BMI is the primary eligibility criterion. You generally need a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Lower thresholds apply for certain ethnic groups. Your GP or prescriber will assess your individual eligibility.
Will the cost of the injection stay the same each month?
Yes, the monthly cost remains consistent once you start a specific dose. However, costs differ between providers and doses — higher doses are more expensive. You can shop around private providers to compare pricing.
What should I do if I'm unsure about my healthy weight range?
Calculate your BMI using our free tool to see where you fall on the NHS healthy weight range for your height. This shows your current category and the weight range considered healthy for your size, helping you and your GP decide on next steps.
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.