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 Norm Data — Understanding Healthy Weight Ranges in the UK
BMI norm data refers to the standard healthy weight ranges and categories used to assess adult health in the UK. According to NHS guidelines, a healthy BMI falls between 18.5 and 24.9 for most adults, though lower thresholds apply to South Asian, Chinese, Black African, and Black Caribbean populations due to increased health risks at lower BMI levels. Understanding these norm data helps you see where your weight sits and whether lifestyle changes or medical support might be beneficial. Use our free BMI calculator above to find your personal BMI instantly and see which category you fall into.
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 Standard Ranges
The NHS BMI formula is straightforward: weight (kg) divided by height (metres) squared. This produces a single number that classifies your weight status according to standard bmi categories uk health authorities use.
- Underweight: BMI below 18.5 — may indicate malnutrition or health concerns
- Healthy weight: BMI 18.5–24.9 — the healthy bmi target for most adults
- Overweight: BMI 25.0–29.9 — above ideal but not yet obese; overweight bmi threshold starts here
- Obese Class I: BMI 30.0–34.9 — increased health risks
- Obese Class II: BMI 35.0–39.9 — significantly increased health risks
- Severely obese: BMI 40.0+ — highest health risk category
For South Asian, Chinese, Black African, and Black Caribbean adults, the nhs bmi thresholds shift lower: healthy weight is 18.5–22.9, and overweight begins at 23.0. These adjusted ranges reflect higher cardiovascular and metabolic risk in these populations at standard BMI levels. Convert your weight using our weight converter to ensure you're using the correct measurements for your BMI calculation.
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.
BMI Limitations and What Norm Data Doesn't Tell You
Although bmi norm data provides a useful screening tool, bmi limitations are significant. BMI does not distinguish between muscle and fat — athletes may have a high BMI despite low body fat. It also ignores where fat is stored; waist circumference and waist-to-hip ratio are often more predictive of cardiovascular risk than BMI alone. BMI is less accurate for elderly people (who have naturally lost muscle), during pregnancy, and for very tall or very short individuals.
For a fuller health picture, combine your BMI with waist measurement. The NHS recommends measuring your waist at the narrowest point: increased risk begins at 94cm (37in) for men and 80cm (31.5in) for women. Your GP can help interpret your personal norm data in context of your medical history, family genetics, and overall health. Use our bmi calculator above to find your starting point, then discuss the results with your healthcare provider.
- 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 normal BMI according to NHS norm data?
According to NHS guidelines, a normal or healthy BMI is between 18.5 and 24.9 for most UK adults. For South Asian, Chinese, Black African, and Black Caribbean populations, the healthy range is slightly lower: 18.5 to 22.9. These ranges are based on epidemiological data showing health risks increase outside these boundaries.
How do I calculate my BMI using the standard formula?
The BMI formula is weight (kg) divided by height (metres) squared. For example, a person weighing 70kg and 1.73m tall would calculate: 70 ÷ (1.73 × 1.73) = BMI of 23.4 (healthy weight). Our free BMI calculator above does this instantly — just enter your measurements.
Why are BMI thresholds lower for some ethnic groups in UK norm data?
Research shows South Asian, Chinese, Black African, and Black Caribbean populations have higher risk of type 2 diabetes and cardiovascular disease at lower BMI levels compared to European populations. Lower NHS thresholds (healthy range 18.5–22.9 instead of 18.5–24.9) account for this increased metabolic risk and allow earlier intervention.
What does it mean if my BMI is outside the normal range?
If your BMI is above 24.9 (or 22.9 if you're from a lower-threshold ethnic group), you may be at increased health risk. This doesn't mean you need immediate treatment, but discussing your BMI norm data with your GP is wise. They can assess your overall health, family history, and whether lifestyle changes or medical support would help.
Is BMI the only measure of healthy weight I should use?
No. BMI is a useful screening tool but has limitations. Waist circumference is equally important — high central fat carries greater health risk. Muscle mass, body composition, blood pressure, and cholesterol also matter. Your GP can provide personalised interpretation of your BMI norm data alongside these other factors.
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.