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
Health Calculators for UK Adults
Health calculators are essential tools for understanding your weight, BMI, and overall health status according to NHS guidelines. Whether you're monitoring your wellbeing or exploring weight management options, having access to accurate, free calculators makes it simple to track your health metrics in UK measurements. Our suite of free tools helps you convert weight between stone, pounds, and kilograms, calculate your BMI using NHS standards, and estimate potential weight loss outcomes with evidence-based projections. Using a personalised UK health guide approach, these calculators empower you to make informed decisions about your health alongside professional medical advice.
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.
NHS-Aligned Calculators for Your Health
MyWeightCheck provides free health calculators designed specifically for UK adults, using NHS health advice standards and UK measurements. Our BMI calculator applies NHS guidance, including ethnicity-adjusted thresholds for South Asian, Chinese, Black African, and Black Caribbean adults who face higher health risks at lower BMI levels.
- BMI Calculator: Calculate your body mass index instantly using your height and weight. The calculator shows your BMI category (healthy weight, overweight, or obese) and your healthy weight range according to NHS standards.
- Weight Converter: Convert between kg, stone, and pounds effortlessly. Essential for understanding UK health information that often uses different measurement systems.
- GLP-1 Weight Loss Calculator: If you're exploring prescription weight management options like Mounjaro or Wegovy, this calculator helps estimate potential weight loss based on clinical trial data — though individual results vary significantly.
- Progress Tracker: Log your weight over time and visualise your journey towards your health goals with our free tracking tool.
All calculators are evidence-based, free to use, and designed to complement—not replace—advice from your GP or healthcare professional.
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.
Using Calculators as Part of Your Health Journey
Health calculators are most useful when combined with professional medical advice and sustainable lifestyle changes. If your BMI falls outside the healthy range, or if you have weight-related health conditions, speaking with your GP is the first step. Your GP can refer you to NHS tier 3 weight management services if appropriate, where you may receive additional support including prescription options.
For those exploring weight loss medication like Mounjaro or Wegovy, our GLP-1 weight loss calculator provides context based on clinical trial averages—though a licensed prescriber must assess your individual eligibility and suitability. Use these free calculators to understand your baseline, track your progress, and start conversations with your healthcare team about the best 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.
Are these health calculators accurate?
Yes. Our BMI calculator uses NHS guidelines and official conversion formulas. However, BMI has limitations—it doesn't distinguish between muscle and fat. For personalised health assessment, always consult your GP, especially if you have concerns about your weight or health.
What does my BMI number actually mean?
BMI categories (healthy weight, overweight, obese) are based on NHS standards. A healthy BMI is 18.5–24.9 for most adults; lower thresholds apply for certain ethnic groups. Your GP can explain what your BMI means for your individual health and any next steps.
Can I use these calculators if I'm pregnant or have medical conditions?
BMI calculators aren't suitable during pregnancy. If you have medical conditions affecting weight, metabolic health, or mobility, speak with your GP before using health calculators or making health changes based on calculator results.
How often should I use the progress tracker?
Weekly weigh-ins work well for most people, though some prefer monthly tracking. Consistency matters more than frequency. Expect natural weight fluctuations; focus on trends over weeks, not daily changes.
Do these calculators tell me if I need weight loss medication?
No. Only a licensed prescriber can assess your eligibility for medication like Mounjaro or Wegovy following a clinical assessment. Our weight loss calculator provides educational context based on trial data, but individual results vary. Your GP can discuss whether prescription options are appropriate for you.
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.