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
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Understanding the NHS BMI Graph
The NHS BMI graph is a visual tool that shows how your body weight relates to your height and helps determine whether you fall into a healthy weight range. Unlike a simple BMI formula, the graph makes it easy to see at a glance which BMI category you sit in — from underweight through to severely obese. This guide explains how to read the NHS BMI graph, what the different zones mean, and why it matters for your health. You can also use our free BMI calculator above to find your exact BMI instantly without needing to plot a graph.
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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 to Read an NHS BMI Graph
An NHS BMI graph plots weight (in kilograms) on the vertical axis against height (in centimetres) on the horizontal axis. To use it, locate your height on the bottom, move upwards to where it meets your weight, and read across to find your BMI number and category.
The graph is divided into coloured zones representing different BMI categories:
- Underweight: BMI below 18.5 (usually blue or green)
- Healthy weight: BMI 18.5–24.9 (green zone)
- Overweight: BMI 25.0–29.9 (yellow or amber zone)
- Obese (Class I): BMI 30.0–34.9 (orange zone)
- Obese (Class II): BMI 35.0–39.9 (red zone)
- Severely obese (Class III): BMI 40.0+ (dark red zone)
This visual representation helps you quickly see which healthy BMI range you're aiming for and understand the relationship between your height and weight.
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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.
BMI Graph Limitations and What Else Matters
While an NHS BMI graph is useful for screening, it has important limitations. BMI does not distinguish between muscle and fat — an athlete with significant muscle mass may have a high BMI but low body fat. The graph also doesn't account for where fat is stored around your body.
To get a complete picture of your health, the NHS also recommends measuring your waist circumference. For men, increased risk starts above 94cm (37 inches); for women above 80cm (31.5 inches). Use our free weight converter to track your progress in your preferred units, and discuss your personal health context with your GP who can assess factors the graph alone cannot show.
- 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.
What does my BMI number mean if I'm on the NHS BMI graph?
Your BMI number tells you where you fall on the weight spectrum. A BMI of 22 (within the healthy range) suggests your weight is proportionate to your height. A BMI of 28 (overweight range) indicates increased health risks. The NHS uses these categories to guide when lifestyle changes or medical support might help. Your GP can explain what your specific number means for your health.
Is the NHS BMI graph the same for all adults?
The standard NHS BMI graph applies to most UK adults aged 18–65. However, the NHS recommends lower BMI thresholds for adults of South Asian, Chinese, Black African, and Black Caribbean heritage, as these groups face higher cardiovascular and diabetes risk at lower BMI levels. Always discuss your individual results with your GP.
Can I use the BMI graph if I'm very tall or very short?
Yes, the graph includes a full range of heights and weights. However, BMI is less accurate at the extremes of height. Very tall or very short individuals may find that the BMI graph doesn't fully reflect their healthy weight range. Your GP can discuss whether BMI is the best measure for you personally.
What's the difference between using the NHS BMI graph and a BMI calculator?
The graph is a visual tool that helps you see the relationships between height and weight at a glance. A BMI calculator (like the free tool on this page) gives you a precise numerical BMI result. Both methods use the same formula and categories — the calculator is simply faster and more accurate for individual measurements.
Why does the NHS use BMI if it has limitations?
BMI is a quick, non-invasive screening tool that works well for most of the population. It helps identify people who may benefit from weight management support. However, the NHS always recommends combining BMI assessment with other measures like waist circumference and a discussion with your GP, who can consider your complete health picture.
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.