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 Are Weight Loss Injections in the UK?
Weight loss injections like Mounjaro and Wegovy are available in the UK through both NHS and private routes, with costs varying significantly between them. On the NHS, prescription weight loss injections are provided free once approved by specialist services. Through private prescribing, costs typically range from £129 to £320 per month depending on the medication and dose. Understanding your BMI and eligibility is the first step towards accessing the right treatment for your situation. Use our free BMI calculator to determine where you fall on the healthy weight scale, then explore your options based on your individual health profile and budget.
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.
What Your BMI Tells You About Weight Loss Options
Your BMI (body mass index) determines whether you may be eligible for prescription weight loss injections in the UK. Adults with a BMI of 30 or above, or 27 or above with weight-related health conditions, may qualify for treatment. The BMI calculator on this page shows your personal BMI instantly and explains where you fall within NHS healthy weight ranges.
- BMI under 25: Generally in the healthy weight range — lifestyle changes may be sufficient
- BMI 25–29.9: Overweight category — your GP can discuss options with you
- BMI 30 or above: Eligible for NHS referral to specialist weight management services or private prescription assessment
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — eligibility may start at a BMI of 27.5 or above. Calculate your BMI now using the calculator above to see where you stand and what your next steps might be.
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.
Taking Action: From BMI to Treatment Access
Once you know your BMI and understand your eligibility, the next step depends on your preference and circumstances. NHS route: Ask your GP for a referral to your local tier 3 specialist weight management service — this is free but waiting lists vary by region. Private route: Register with a licensed online prescriber, complete a clinical assessment, and receive a prescription if appropriate — typically available within days. Whichever route you choose, weight loss medications work best alongside a reduced-calorie diet and increased physical activity. Track your progress using our free progress tracker to monitor results over time, and remember that individual outcomes vary — your GP or prescriber can give personalised guidance on what to expect.
- 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 on the NHS?
Weight loss injections are free on the NHS if you are approved by a specialist weight management service. Your GP can refer you, though waiting times vary by region. Some areas have longer waiting lists than others, so check with your local integrated care board for current timescales.
What is the typical private cost for Mounjaro or Wegovy?
Private costs typically range from £129 to £320 per month depending on the medication, dose, and provider. Mounjaro and Wegovy are both once-weekly injections. Initial consultations are usually £50–£100, and some providers offer discounts for longer-term packages or bulk purchases.
Does my BMI affect whether I can access weight loss injections?
Yes — in the UK, adults with a BMI of 30 or above, or 27 or above with weight-related health conditions, typically qualify. Lower thresholds apply for certain ethnic groups. Use the BMI calculator on this page to check your personal BMI and understand your eligibility.
Can I get weight loss injections through my GP without a specialist referral?
Currently, weight loss injections are typically prescribed through NHS tier 3 specialist services, not standard GP prescriptions. However, you can access them privately without an NHS referral — licensed online prescribers offer clinical assessments and prescriptions if you meet the criteria.
What is the healthy weight range for my height?
A healthy BMI is between 18.5 and 24.9 according to NHS guidelines. To find your ideal weight for height, calculate your BMI using the tool on this page — it will show you the healthy weight range and how close you are to it. Your GP can also provide personalised 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.