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 within UK health guidelines. MyWeightCheck provides free, easy-to-use calculators designed specifically for UK measurements—stone, pounds, and kilograms. Whether you're checking your BMI, converting between weight units, or projecting potential weight loss with GLP-1 medication, our calculators deliver instant, accurate results aligned with NHS guidance. All tools are completely free and require no registration or personal data.
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 UK Health Calculators Can Help You With
BMI Calculator: Calculate your body mass index instantly using your height and weight. Our BMI calculator uses NHS categories and includes ethnicity-adjusted thresholds for South Asian, Black African, Black Caribbean, and Chinese adults—because health risk varies by ethnic background at the same BMI.
Weight Converter: Convert between kg, stone, and pounds seamlessly. UK adults often use stone and pounds, whilst NHS records use kilograms. Our converter handles all combinations with precision, so you always know your weight in whichever units matter to you.
GLP-1 Weight Loss Calculator: If you're considering prescription weight loss medication like Mounjaro or Wegovy, our GLP-1 calculator helps you estimate potential weight loss based on clinical trial data. Results vary by individual, but the calculator gives evidence-based projections.
Progress Tracker: Log your weight loss journey over time and watch your progress. Tracking builds accountability and motivation, and our free tool makes it simple.
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.
Why Use Our UK Health Calculators?
Our calculators are built specifically for UK adults and NHS health thresholds. All tools use accurate conversion formulas and are aligned with NHS weight management guidance, NICE recommendations, and current UK health standards.
Unlike generic US-based calculators, ours use UK measurements (stone, pounds, kilograms) and reflect UK healthy weight ranges. If you're exploring weight loss with medication, our GLP-1 weight loss calculator draws from clinical trial data for Mounjaro and Wegovy—the UK-licensed weight management injections.
Every calculator is free, no sign-up required, and updated regularly with the latest UK health guidance. Use them as many times as you need.
- 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 calculators accurate?
Yes. Our BMI calculator uses the standard formula (weight ÷ height²) aligned with NHS categories. Our weight converter uses exact conversion factors (1 kg = 0.157473 stone). Our GLP-1 calculator draws from published clinical trial data. However, calculators provide general guidance—your GP can give personalised advice based on your individual health.
Do I need to create an account to use these calculators?
No. All MyWeightCheck calculators are completely free and require no registration, login, or personal data. You can use them instantly and as often as you like.
Which calculator should I use first?
Start with the BMI calculator if you want to understand your weight category according to NHS guidelines. Then use the weight converter if you prefer to see your weight in different units. If you're considering GLP-1 medication, try our weight loss calculator alongside the BMI calculator to get a full picture.
What if my BMI is in the healthy range but I still want to lose weight?
That's fine. Weight loss goals are personal, and many people lose weight for reasons beyond BMI—including fitness, energy, or reducing risk factors like blood pressure or cholesterol. Discuss your goals with your GP, who can advise whether weight loss is appropriate for you.
Can I use these calculators if I'm pregnant or under 18?
BMI categories change during pregnancy, and children use age-specific growth charts rather than adult BMI ranges. These calculators are designed for non-pregnant adults. Pregnant women and young people should consult their GP or midwife for 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.