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
NHS BMI Table — UK Health Categories Explained
The NHS BMI table divides adults into four main weight categories based on their BMI score. A healthy BMI according to NHS guidelines is between 18.5 and 24.9, while higher scores indicate overweight or obesity. This guide explains the NHS BMI categories used across the UK, how to find your BMI range, and why BMI is useful alongside other health measures. Use our free BMI calculator above to check your personal BMI instantly against the NHS table.
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 BMI Categories and Ranges
The NHS BMI table classifies adult weight into four main categories. A BMI below 18.5 is underweight, 18.5–24.9 is healthy weight, 25.0–29.9 is overweight, and 30.0 or above is obese. Within the obese category, the NHS further divides this into Class I (30.0–34.9), Class II (35.0–39.9), and Class III or severe obesity (40.0+). These NHS thresholds help GPs identify whether your weight poses health risks. The BMI formula used is simple: weight in kilograms divided by height in metres squared. For example, an adult who weighs 70kg and is 1.75m tall would have a BMI of approximately 22.9, which falls in the healthy weight range according to the NHS BMI table.
- Underweight: BMI below 18.5
- Healthy weight: BMI 18.5–24.9
- Overweight: BMI 25.0–29.9
- Obese Class I: BMI 30.0–34.9
- Obese Class II: BMI 35.0–39.9
- Severe obesity: BMI 40.0 and above
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.
Important BMI Limitations and Health Context
While the NHS BMI table is a useful screening tool, it has important limitations. BMI does not distinguish between muscle and fat—athletes or very muscular individuals may have a high BMI but low body fat. The table also does not account for where fat is stored; waist circumference is equally important for assessing health risk. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds because these groups face higher cardiovascular and diabetes risk at the same BMI levels. Your GP can provide personalised advice about what your BMI means for your individual health. Use our free weight converter to understand your weight in different units, and discuss your results with your healthcare provider for a complete health picture.
- 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 is a healthy BMI according to the NHS?
According to the NHS BMI table, a healthy BMI for most UK adults is between 18.5 and 24.9. If your BMI falls within this range, your weight is generally considered healthy for your height. However, your GP may also consider your waist measurement, fitness level, and overall health when assessing your weight.
How do I calculate my BMI using the NHS formula?
The NHS BMI formula is: weight (kg) ÷ height (m)². For example, if you weigh 70kg and are 1.75m tall, your BMI is 70 ÷ (1.75 × 1.75) = 22.9. Our free BMI calculator above does this instantly—just enter your weight and height to see your result against the NHS table.
Does the NHS BMI table apply to everyone?
The standard NHS BMI table applies to most UK adults. However, the NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, or Black Caribbean heritage due to increased health risks at lower BMI levels. Children use different age and sex-specific growth charts, not adult BMI categories.
What should I do if my BMI is above the healthy range?
If your BMI is above 24.9, speak to your GP. They can assess your individual health, discuss your weight, and suggest appropriate steps such as lifestyle changes, referral to a weight management service, or other support. Even a 5–10% reduction in body weight can have meaningful health benefits.
Why is waist measurement important alongside the NHS BMI table?
The NHS BMI table measures overall weight but does not show where fat is stored. Excess abdominal fat is linked to higher cardiovascular and diabetes risk. The NHS recommends checking waist circumference: men over 94cm and women over 80cm have increased health risk, regardless of BMI.
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.