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 Are MyWeightCheck's Tools?
MyWeightCheck provides four free, easy-to-use health calculators designed specifically for UK adults. These tools help you understand your weight, health status, and potential outcomes with evidence-based guidance aligned with NHS standards. Whether you're converting between stone and kilograms, checking your BMI, exploring weight loss options, or tracking progress, our tools give you personalised information without any cost or sign-up required.
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.
MyWeightCheck's Four Core Health Tools
BMI Calculator: Instantly calculate your Body Mass Index using your height and weight in UK measurements (stone, pounds, or kilograms). The calculator shows your BMI category according to NHS guidelines, with ethnicity-adjusted thresholds for South Asian, Chinese, Black African, and Black Caribbean adults — groups who face higher health risks at lower BMI levels. Results include your healthy weight range and practical context about what your BMI means for your health.
- Uses NHS-standard categories
- Accounts for ethnicity-adjusted thresholds
- Shows healthy weight range instantly
- Explains BMI limitations and waist measurement context
Weight Converter: Convert between kilograms, stone, and pounds instantly — useful because UK adults often use stone while NHS records use kilograms. Our converter handles all combinations: kg to stone, stone to pounds, or mixed measurements like "11 stone 7 pounds" to kg.
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.
GLP-1 Weight Loss Calculator and Progress Tracker
GLP-1 Weight Loss Calculator: If you're considering prescription weight loss medications like Mounjaro or Wegovy, this calculator estimates potential weight loss based on clinical trial data. It projects results at different doses alongside reduced-calorie diet and increased physical activity — helping you understand realistic outcomes. Results are based on SURMOUNT and STEP clinical trials, with clear messaging that individual results vary significantly.
Progress Tracker: Log your weight, date, and notes to track your weight loss journey over time. Visualise your progress with simple charts and stay motivated with a free, private tracking tool. Perfect for anyone following NHS guidance on sustainable weight loss (0.5–1 kg per week) or monitoring results with weight management medication.
All tools use UK measurements (stone, pounds, kilograms, centimetres) and are aligned with NHS guidance, not American standards.
- 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.
Are MyWeightCheck's tools free to use?
Yes, all four tools are completely free. No sign-up, no cost, no hidden fees. MyWeightCheck is an independent UK health information website — we don't sell medication or services, only provide evidence-based calculators and information.
Why does the BMI calculator have ethnicity-adjusted thresholds?
The NHS recommends lower BMI thresholds for South Asian, Chinese, Black African, and Black Caribbean adults because these groups have higher risk of type 2 diabetes and cardiovascular disease at the same BMI as other populations. Ethnicity-adjusted thresholds provide more accurate health context.
How accurate is the GLP-1 weight loss calculator?
The calculator is based on clinical trial averages (SURMOUNT-1 for Mounjaro, STEP-1 for Wegovy), but individual results vary significantly. It's a projection tool, not a assures. Always consult your prescriber for personalised advice about potential outcomes.
Can I use the progress tracker on my phone?
Yes, the progress tracker works on desktop, tablet, and mobile devices. Your data is saved in your browser, so you can log entries anytime, anywhere — no app download needed.
Should I consult my GP before using these tools?
These tools are informational and help you understand your health context. If you're concerned about your weight, BMI, or considering weight loss medication, always discuss with your GP first. They can give personalised advice based on your medical history.
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.