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
Free Health Calculators for UK Adults
Health calculators are essential tools for understanding your weight and fitness. Whether you're checking your BMI, converting between stone and kilograms, or exploring weight loss options, MyWeightCheck offers free, easy-to-use calculators aligned with NHS guidance. These tools help you get accurate, personalised health information quickly—no registration required. Start with your measurements today to discover your healthy weight range and take the first step towards better health.
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 Health Calculators Are Available?
MyWeightCheck provides several free health calculators designed specifically for UK adults. Our BMI calculator works out your body mass index in seconds using your height and weight, comparing your result against NHS healthy weight categories. The weight converter instantly changes between kilograms, stone, and pounds—the UK's preferred measurements. For those exploring weight loss options, our GLP-1 weight loss calculator estimates potential weight loss at different medication doses based on clinical trial data from semaglutide (Wegovy) and tirzepatide (Mounjaro). Finally, our progress tracker lets you log weekly weight changes and visualise your progress over time. All calculators use evidence-based formulas and align with NHS health guidance.
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.
How to Use These Tools for Better Health Decisions
Start by calculating your current BMI using our free calculator above—this gives you an instant snapshot against NHS weight categories. Use the weight converter to switch between units if you're more familiar with one measurement system. If you're interested in prescription weight loss medications like Wegovy or Mounjaro, our GLP-1 calculator shows estimated weight loss based on your starting weight and chosen dose, using real clinical trial results. Individual results vary, and any medication requires a clinical assessment from a GP or licensed prescriber. For long-term progress, use the progress tracker to record weekly weights and spot trends—even small consistent losses improve health outcomes.
- 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 calculators accurate?
Yes. Our BMI calculator uses the official NHS formula. Our weight converter uses exact metric-to-imperial conversions. Our GLP-1 calculator uses clinical trial averages from STEP and SURMOUNT studies—though individual results vary. Our progress tracker simply records your entered data. All tools align with NHS healthy weight guidance.
Do I need to create an account to use the calculators?
No. All MyWeightCheck calculators are completely free and require no registration, login, or personal information. Use them as many times as you need.
What does the BMI calculator tell me?
Your BMI (body mass index) compares your weight to your height. Our calculator shows your BMI number and which NHS category it falls into: underweight, healthy weight, overweight, or obese. It also shows your healthy weight range for your height.
Can the GLP-1 calculator predict my exact weight loss?
No. The GLP-1 calculator shows average weight loss from clinical trials alongside lifestyle changes. Individual results vary significantly based on metabolism, diet, exercise, and genetics. It's an estimate for guidance only—always discuss realistic expectations with your prescriber.
Is the weight loss calculator the same as medical advice?
No. The calculator is informational only and shows clinical trial averages. It does not constitute medical advice. You must have a clinical assessment with a GP or licensed prescriber before starting any weight loss medication.
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.