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
BMI Index Chart in Kg — NHS Categories and Health Guidance
The body mass index (BMI) is a screening tool that uses your weight in kilograms and height to assess whether you're at a healthy weight. The NHS provides a standardised BMI index chart that categorises adults into ranges from underweight through to severely obese. Understanding your BMI and what the NHS recommends can help you make informed decisions about your health. Use our free BMI calculator above to find your personal BMI instantly, then refer to the NHS categories below to understand what it means.
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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 What They Mean
The NHS BMI categories for adults are based on the following ranges in kilograms:
- Below 18.5: Underweight — may indicate insufficient body weight for optimal health
- 18.5 to 24.9: Healthy weight — the target range recommended by NHS and NICE
- 25.0 to 29.9: Overweight — increased health risk; lifestyle changes recommended
- 30.0 to 34.9: Obese (Class I) — elevated risk of weight-related health conditions
- 35.0 to 39.9: Obese (Class II) — significant health risks; GP assessment recommended
- 40.0 and above: Severely obese (Class III) — high risk; medical intervention may be needed
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds due to higher health risks at the same BMI levels. The healthy weight range for these groups starts at 18.5 and extends only to 22.9, with overweight beginning at 23.0.
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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.
NHS Weight Management Pathway and When to Seek Help
The NHS offers a structured weight management pathway with four tiers of support. Tier 1 includes self-help resources and digital tools like the calculators on this page. Tier 2 provides primary care-based programmes and behaviour change support through your GP. Tier 3 is specialist multidisciplinary weight management services, where prescription weight loss medication may be considered. Tier 4 includes bariatric surgery for severe obesity with significant health complications.
If your BMI is above 25, or you have concerns about your weight and health, speak to your GP. They can assess whether you'd benefit from support at a specific tier and discuss options 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.
What is a healthy BMI according to the NHS?
The NHS defines a healthy BMI as 18.5 to 24.9 kg/m² for most adults. This range reflects the weight associated with the lowest health risks. For South Asian, Chinese, Black African, and Black Caribbean adults, a healthy BMI is 18.5 to 22.9. Use our free BMI calculator to check your personal BMI instantly.
What does an overweight BMI mean according to NHS guidance?
An overweight BMI (25.0 to 29.9) indicates increased risk of health conditions like type 2 diabetes, high blood pressure, and heart disease. The NHS recommends lifestyle changes including diet and physical activity. A GP can advise you on the best approach for your situation.
Why does the NHS have different BMI categories for different ethnicities?
Research shows that people of South Asian, Chinese, Black African, and Black Caribbean heritage have higher risks of type 2 diabetes and cardiovascular disease at lower BMI levels. The NHS adjusted recommendations reflect this increased health risk and allow earlier intervention.
How do I use this BMI index chart in kg with my weight?
Find your weight in kilograms on the left side of the chart, then locate which BMI category it falls into based on your height. Our BMI calculator above does this automatically — simply enter your weight in kg and height, and it will show you your exact BMI and category.
What should I do if my BMI is above 30 according to the NHS?
If your BMI is 30 or above, the NHS recommends speaking to your GP. They can assess your overall health, discuss whether prescription weight loss medication or specialist support might help, and guide you through the weight management pathway appropriate to your needs.
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.