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
Weight Management & UK Health Information
Managing your weight effectively requires understanding your personal health context and having access to reliable UK health guidance. Whether you're exploring weight loss options, understanding your BMI, or looking for NHS-aligned advice, this guide provides evidence-based information to support your health decisions. Our free BMI calculator and weight converter help you assess your current weight status using UK measurements, while practical guidance throughout this page connects you to the support and tools you need.
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 Healthy Weight Range
A healthy weight depends on your height, age, and overall health rather than a single target number. The NHS defines a healthy BMI range of 18.5 to 24.9 for most UK adults, though lower thresholds apply for people of South Asian, Chinese, Black African, or Black Caribbean heritage due to higher health risks at lower BMI levels.
- Healthy weight range: Use our free BMI calculator above to find your personal healthy weight range based on your height.
- Individual variation: Factors like muscle mass, bone density, and overall fitness mean the healthy range isn't one fixed weight.
- Waist circumference matters: For men, over 94 cm indicates increased risk; for women, over 80 cm is a health consideration flag.
Rather than focusing only on the number on the scales, NHS health advice emphasises how you feel, your energy levels, and whether weight-related health conditions are improving.
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.
Weight Management Options & Support
Sustainable weight management typically combines dietary changes, physical activity, and behaviour support. The NHS weight management pathway includes tier 1 self-help resources, tier 2 community programmes, and tier 3 specialist services where prescription weight loss medications may be considered.
For those with a BMI of 30 or above, or 27–29.9 with weight-related health conditions, prescription weight loss treatments may be an option following clinical assessment. Our GLP-1 weight loss calculator can help you explore potential outcomes at different treatment doses. Always discuss weight management plans with your GP, who can assess your individual circumstances and recommend the most suitable approach for your health goals.
- 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's the difference between BMI and healthy weight?
BMI is a screening tool using height and weight to estimate health risk, but it doesn't account for muscle mass or fat distribution. A healthy weight range is personalised based on your height, health conditions, and individual circumstances. Use our free BMI calculator to find your range, then discuss your personal target with your GP.
How quickly should I aim to lose weight safely?
The NHS recommends losing 0.5 to 1 kg (1–2 lbs) per week for sustainable results. Faster weight loss can lead to muscle loss and nutritional deficiencies. A calorie deficit of around 500 kcal daily typically supports this rate. Work with a healthcare professional to set safe, realistic goals.
Can I use our weight converter to track my progress?
Yes — our free weight converter instantly switches between kg, stone, and pounds, making it easy to track your progress in whichever units you prefer. Many UK users find tracking in both stone and kg helpful for motivation and accountability throughout their journey.
Are prescription weight loss medications available on the NHS?
GLP-1 medications like Mounjaro and Wegovy are available through NHS specialist tier 3 weight management services, though availability and waiting times vary by region. Private prescribing is also available through UK-licensed prescribers. Your GP can advise on NHS options in your area.
What if I need support with weight management long-term?
Long-term success requires ongoing support. This might include regular GP reviews, community weight management groups, digital apps, or specialist services. Combining medication (if appropriate) with behaviour change support, diet adjustments, and physical activity gives the best outcomes. Your GP can signpost you to local resources.
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.