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, BMI, and eligibility for weight management support. MyWeightCheck provides free, NHS-aligned calculators designed specifically for UK measurements—stone, pounds, and kilograms. Whether you're checking your BMI, converting between weight units, or exploring GLP-1 medication options, our calculators give you instant, personalised results without requiring any registration or payment.
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 offers several free health calculators to help you understand your weight and health:
- BMI Calculator — Instantly calculates your Body Mass Index using your height and weight. Results align with NHS guidelines and include ethnicity-adjusted thresholds for South Asian, Chinese, Black African, and Black Caribbean adults, who face higher health risks at lower BMI levels.
- Weight Converter — Converts between kilograms, stone, and pounds instantly. Useful for understanding your weight in the UK measurements you're familiar with.
- GLP-1 Weight Loss Calculator — Estimates potential weight loss outcomes with Mounjaro (tirzepatide) or Wegovy (semaglutide) based on your current weight and chosen dose. Results are based on clinical trial data and individual outcomes will vary.
- Progress Tracker — Logs your weight loss journey over time, helping you monitor trends and stay motivated.
All calculators are completely free and provide gradual improvement without requiring personal data to be saved.
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 Calculators Effectively
For best results, use your most accurate current weight and height measurements. Our BMI calculator is ideal for baseline health assessment, whilst the weight converter helps you understand your weight in multiple UK measurement formats. If you're considering prescription weight loss medication, our GLP-1 weight loss calculator can show projected outcomes at different doses—though individual results vary significantly.
Remember that calculator results are informational only. For personalised health advice, always consult your GP. A prescriber can assess whether prescription weight loss treatment is suitable for you based on your individual health circumstances.
- 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 these health calculators accurate?
Yes—our calculators use medically recognised formulas and NHS guidelines. BMI calculations follow standard clinical methods. However, BMI has limitations (it doesn't distinguish muscle from fat) and individual health varies. Your GP can provide personalised interpretation of your results.
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 data. Your results are calculated instantly and not stored.
Can the GLP-1 weight loss calculator predict my exact weight loss?
No—the GLP-1 calculator shows average projected outcomes based on clinical trials. Individual results vary significantly depending on your metabolism, adherence, lifestyle, and other factors. Always discuss realistic expectations with your prescriber.
What should I do with my calculator results?
Use results as a starting point for understanding your health. If your BMI falls outside the healthy range, or if you're interested in weight loss support, discuss your results with your GP. They can provide personalised guidance and refer you to appropriate services.
Are these calculators suitable for children?
The BMI calculator should not be used for children under 18—children use different, age-specific growth charts. Always consult your child's GP or health visitor for children's weight assessment.
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.