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
Width to Circumference Calculator for UK Health
A width to circumference calculator helps you understand your body measurements and what they mean for your health. While most UK health assessments use direct circumference measurements like waist circumference, understanding the relationship between width and circumference is useful when tracking body composition changes. This free UK health guide explains how these measurements work together, why waist circumference matters according to NHS guidance, and how they relate to your overall weight management and cardiovascular health risk assessment.
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.
How Width and Circumference Measurements Work
Width vs. circumference: Width refers to the distance across a body part (like chest or waist width), while circumference is the measurement around it. A body part's width depends on its shape and density, so two people with the same width may have different circumferences.
The NHS emphasises waist circumference as a key health indicator because it reflects abdominal fat distribution, which is strongly linked to cardiovascular disease and type 2 diabetes risk. Waist circumference is measured at the midpoint between your lowest rib and hip bone, standing upright and relaxed.
- Men: increased risk above 94cm (37in); high risk above 102cm (40in)
- Women: increased risk above 80cm (31.5in); high risk above 88cm (34.5in)
- For South Asian, Chinese, Black African, and Black Caribbean adults, thresholds are lower
Chest width and circumference, by contrast, relate more to overall body composition and muscle mass than health risk, and are less commonly used in UK health assessments.
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 Measurements for Health and Weight Management
Your waist circumference, combined with your BMI, gives a more complete picture of your health than either measurement alone. Our free BMI calculator helps you assess healthy weight range for your height according to NHS guidelines, and waist measurement adds context about where your body stores fat.
If your waist circumference falls into the increased or high-risk category, your GP can discuss lifestyle changes, weight management options, or nhs health advice tailored to you. Progressive weight management through sustainable dietary changes and physical activity can help reduce waist circumference and lower cardiovascular risk.
MyWeightCheck's free weight converter and progress tracker help you monitor changes over time using UK measurements you understand — stone, pounds, and centimetres. Tracking both weight and circumference changes gives motivation and shows health improvements even when the scale moves slowly.
- 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.
Why is waist circumference more important than overall weight?
Waist circumference indicates where fat is stored. Abdominal fat (around organs) carries greater health risks than fat stored elsewhere, even at the same overall weight. NHS guidance uses waist circumference alongside BMI because it directly predicts cardiovascular and diabetes risk better than weight alone.
How do I measure my waist circumference accurately?
Stand upright and relaxed. Place a soft measuring tape at the midpoint between your lowest rib and the top of your hip bone. Measure horizontally around your body without pulling the tape tight. Record the measurement in centimetres. Measure at the same time each day for consistency, ideally in the morning before eating.
What if my waist circumference is in the increased-risk range?
Discuss this with your GP. They can assess your overall health context, blood pressure, cholesterol, and blood sugar. Even a 5–10% reduction in body weight can significantly improve waist circumference and reduce health risk. Your GP can discuss lifestyle changes, nhs health advice, or weight management options suitable for you.
How does waist circumference relate to BMI?
BMI measures weight relative to height but doesn't show where fat is stored. You could have a "healthy" BMI but an unhealthy waist circumference (indicating abdominal fat), or vice versa. Using both together—via our free BMI calculator and direct measurement—gives the clearest picture of your metabolic health and cardiovascular risk.
How often should I measure my waist circumference?
Monthly measurements are useful for tracking progress. Measuring weekly can be demoralising because natural water retention and food intake cause daily fluctuations. Our free progress tracker helps you record both weight and circumference changes over time, showing trends more clearly than single measurements.
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.