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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Calculate Your Weight Percentile — UK Health Context
Understanding where your weight sits relative to other UK adults can be a useful health reference point, though it's important to remember that weight percentiles don't tell the whole story about health. Your actual BMI, waist circumference, and individual health markers matter much more than percentile rankings. This guide explains weight percentiles in a UK context, how they're calculated, and why your GP might discuss them alongside other health measurements. We'll help you understand what your weight percentile means and how it relates to healthy weight management.
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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.
What Is a Weight Percentile and How Is It Calculated?
A weight percentile shows how your weight compares to other people of the same age, sex, and height in a reference population. For example, if you're at the 60th percentile, roughly 60% of people in that demographic weigh less than you, and 40% weigh more.
- Percentiles are calculated using large population datasets, typically from health surveys like the Health Survey for England or UK Biobank
- They differ from BMI — percentiles compare you to actual people, while BMI uses a fixed formula (weight ÷ height²) that applies equally to everyone
- Age and sex matter — weight percentiles are age and sex-specific because men and women typically weigh differently, and weight changes across the lifespan
- Reference populations change — percentiles based on 2010 data may differ from those based on 2024 data as average UK weights have shifted
Percentiles can be useful as a contextual reference, but they should never replace medical assessment. Your GP or a qualified healthcare professional is the best source for personalised guidance about whether your weight is healthy for you.
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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.
Weight Percentile vs BMI — Which Matters More?
Both weight percentiles and BMI have strengths and limitations. BMI is standardised — the same formula applies to all adults regardless of age or gender, making it easier to compare across populations. However, BMI doesn't account for muscle mass or body composition. Weight percentiles are context-specific — they show how you compare to real UK adults, but percentiles shift as populations change and can be influenced by data collection methods.
For practical health purposes, the NHS recommends focusing on BMI alongside waist circumference and your individual health markers (blood pressure, cholesterol, blood sugar) rather than percentiles alone. Use our free BMI calculator above to check your personal BMI, and discuss your weight and health with your GP, who can assess you in context rather than relying on any single measure.
- 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 weight percentile is considered healthy?
There's no single "healthy" percentile — health depends on your individual BMI, fitness, medical conditions, and lifestyle. Being at the 50th or 75th percentile could be perfectly healthy for one person but not optimal for another. NHS guidance focuses on BMI and waist measurement rather than percentiles. Your GP can advise what's healthy for you specifically.
How do I calculate my weight percentile?
Weight percentiles require large population datasets that are typically only available to researchers and health organisations. They're not practical to calculate at home. However, you can use our free BMI calculator and weight converter above to understand your weight in context of NHS healthy weight ranges, which is more actionable for UK health purposes.
Can I use a weight percentile calculator online?
Some online tools estimate weight percentiles using historical UK or international data, but these estimates vary in accuracy depending on the dataset used. For more reliable health information, focus on your BMI using our free BMI calculator, your waist measurement, and your individual health markers. These are more consistent with NHS guidance and more useful for health planning.
Does my weight percentile change if I lose weight?
Yes. Your percentile shifts as your weight changes. For example, if you move from 85kg to 75kg, your percentile ranking relative to the reference population will change. However, the more important measure is whether your new weight falls within a healthy BMI range for your height. Track your progress using our free progress tracker to monitor meaningful health changes.
Why do NHS guidelines use BMI instead of weight percentiles?
BMI is standardised, evidence-based, and consistent across all adults, making it easier for clinicians to identify health risks and provide guidance. Weight percentiles are useful for research but less practical for individual health assessment. The NHS recommends BMI alongside waist measurement and personal health markers, which together give a much clearer picture than percentiles alone.
Ready to take control of your weight loss journey?
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