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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BMI Chart: Weight, Height and Your Health
Understanding your BMI using a weight and height chart is one of the easiest ways to assess whether you're in a healthy range according to NHS guidelines. BMI (body mass index) is calculated from your height and weight using a simple formula, and the resulting number falls into categories that help you understand your health status. This guide explains how to use a BMI chart, what the NHS categories mean, and when you should speak to your GP about your weight.
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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.
NHS BMI Categories and What They Mean
The NHS BMI categories are the official UK standard for assessing whether your weight is healthy for your height. According to NICE guidance, these are the five main BMI ranges:
- Underweight: BMI below 18.5 — may need extra support and nutrition
- Healthy weight: BMI 18.5 to 24.9 — associated with the lowest health risks
- Overweight: BMI 25.0 to 29.9 — increased risk of weight-related conditions
- Obese (Class I): BMI 30.0 to 34.9 — higher health risks present
- Obese (Class II): BMI 35.0 to 39.9 — significant health risks
- Severely obese (Class III): BMI 40.0 and above — substantial health risks
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds because these groups face higher risk of type 2 diabetes and heart disease at lower BMI levels. The healthy BMI range UK for these populations is 18.5 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 and When to Seek Help
If your BMI falls outside the healthy range, the NHS offers a weight management pathway to support you. Your GP can assess your overall health, discuss any weight-related conditions like high blood pressure or type 2 diabetes, and recommend the right approach for you. The NHS pathway includes tier 1 (self-help and digital tools), tier 2 (behaviour change programmes), tier 3 (specialist services where medication may be offered), and tier 4 (bariatric surgery for severe obesity). Use our free BMI calculator above to check your personal BMI instantly. Remember that BMI has limitations — it doesn't distinguish between muscle and fat — so your GP will consider your full health picture, waist measurement, and lifestyle when advising you.
- 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.
How do I calculate my BMI from my weight and height?
The BMI formula is weight (kg) divided by height (metres) squared. For example, if you weigh 70kg and are 1.73m tall: 70 ÷ (1.73 × 1.73) = 23.4 BMI. Our free weight converter and BMI calculator above will calculate this instantly if you prefer.
What is a healthy BMI according to the NHS?
The NHS defines a healthy BMI as 18.5 to 24.9 for most UK adults. For South Asian, Chinese, Black African, and Black Caribbean adults, the healthy range is 18.5 to 22.9 because these groups have higher health risks at lower BMI levels.
Is BMI the only measure of health?
No. BMI is a useful screening tool but has limitations — it doesn't account for muscle mass, bone density, or where fat is stored. The NHS also considers waist circumference, blood pressure, blood sugar, and cholesterol levels when assessing health. Your GP can give personalised advice beyond BMI.
What should I do if my BMI is above 25?
If your BMI is in the overweight or obese range, speak to your GP. They can discuss whether you have any weight-related health conditions, offer lifestyle support, and refer you to NHS weight management services if appropriate. Even modest weight loss (5–10% of body weight) can improve health.
Are BMI thresholds different for children?
Yes. Children use age and sex-specific centile charts, not adult BMI categories. If you're concerned about a child's weight, speak to your GP or health visitor, or use the NHS Healthy Weight Calculator for children.
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.