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 Weight Management
A health calculator is an essential tool for understanding your weight status and tracking your progress towards better health. MyWeightCheck offers free online calculators designed specifically for UK adults, using stone, pounds, and kilograms — the measurements you're familiar with. Whether you're starting a weight loss journey, checking your BMI, or simply monitoring your health, our UK health guide provides the information and tools you need. Aligned with NHS guidance, these calculators help you make informed decisions about your weight management without requiring a prescription or medical visit.
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 Our Health Calculators Can Do for You
MyWeightCheck provides three core calculators to support your health journey:
- BMI Calculator: Instantly calculates your BMI and shows where you fall on the NHS healthy weight scale. Works for all UK measurements and includes ethnicity-adjusted thresholds for South Asian, Chinese, and Black African heritage adults.
- Weight Converter: Converts between kg, stone, and pounds in seconds. No more confusion about what your weight means in different measurements.
- GLP-1 Weight Loss Calculator: If you're considering prescription weight loss medication like Mounjaro or Wegovy, this tool estimates potential outcomes based on clinical trial data and your individual health profile.
All calculators are completely free and require no registration or personal data storage.
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.
NHS Health Advice Integrated Into Every Tool
Our calculators align with NHS guidance on healthy weight, BMI categories, and weight management. Each result includes context — not just a number, but what it means for your health according to current UK health information standards.
- Healthy weight range calculations based on your height
- Waist circumference guidance for cardiovascular risk assessment
- NHS-approved weight loss rate recommendations (0.5–1 kg per week)
- Links to NHS resources for nhs health advice on diet, exercise, and medical support
If you have specific health concerns, our calculators always recommend consulting your GP for personalised nhs guidance tailored to your individual 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.
Is MyWeightCheck a medical service?
No. MyWeightCheck is a free health information website providing educational calculators and UK health context. We do not provide medical advice, diagnoses, or prescriptions. Always consult your GP for medical concerns or before making health decisions.
Which measurements do your calculators use?
All our tools work with UK measurements — stone, pounds, and kilograms. You can enter your weight in any unit and instantly convert or calculate BMI in all formats. No need to remember US conversions.
Can the calculator tell me if I need weight loss medication?
No. Our GLP-1 weight loss calculator is informational only and shows clinical trial averages. Only a UK-licensed prescriber can assess whether you're eligible for medication like Mounjaro or Wegovy. Use it as a starting point for conversation with your GP.
How often should I use the health calculator?
Many people track their weight weekly or monthly using our Progress Tracker alongside the BMI calculator. Regular monitoring helps you see patterns and stay motivated. However, weight fluctuates daily — focus on longer-term trends rather than daily changes.
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.