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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Percentile For Height Calculator — UK NHS Growth Guide
A height percentile calculator shows where your child's height falls compared to other children of the same age and sex in the UK. The NHS uses centile charts to track healthy growth from birth through childhood, and understanding your child's percentile helps identify whether growth is on track. Unlike adult health measures, children's height and weight are assessed using age and sex-specific UK90 growth reference charts rather than fixed categories.
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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.
How UK Growth Percentiles Work
The UK90 growth reference charts are the standard used by NHS health professionals to assess children's growth. Instead of a single "healthy" weight or height, children are measured against percentile bands specific to their age and biological sex.
- Centile 50th: The median — exactly in the middle. Half of children are taller, half shorter.
- Centile 2nd to 98th: The normal healthy growth range. Most children fall between these lines.
- Below 2nd centile: Unusually short for age — your GP may investigate.
- Above 98th centile: Unusually tall for age — typically not a health concern unless there are other symptoms.
Your child's height percentile changes over time as they grow. Staying on the same centile line from year to year is a good sign of healthy, consistent growth, even if it's lower or higher than the average.
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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.
Using Height Percentiles — What Parents Need to Know
If your child's height is consistently below the 2nd centile or above the 98th centile, your GP may want to investigate further — but a single measurement is not enough to trigger concern. What matters most is the growth trend over time. A child tracking along the 10th centile is growing normally if they stay on that line, even though they're shorter than average.
Growth can be affected by genetics (tall or short parents), nutrition, sleep, hormones, and occasionally underlying health conditions. Our free BMI calculator can help parents assess their child's overall health context alongside height and weight, though remember that BMI categories for children differ from adult categories and should be interpreted by your GP or health visitor.
If you have concerns about your child's growth, speak to your health visitor or GP — they can plot your child's measurements on the official NHS growth charts and advise if any investigation is needed.
- 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 height percentile for a child in the UK?
Any percentile between the 2nd and 98th centile is considered a normal, healthy range on UK NHS growth charts. Most children fall between the 10th and 90th centiles. The specific percentile matters less than whether your child is growing consistently along their own centile line over time.
How often should my child's height be measured?
Your health visitor routinely measures your child's height at standard review points — typically at birth, 8–12 weeks, 12 months, 2–3 years, and at school entry (age 4–5). You can also request measurements from your GP at any time if you're concerned.
My child is on the 5th percentile — is that a problem?
Not necessarily. If your child is growing steadily along the 5th percentile, growth is healthy. However, if your child's percentile has recently dropped — for example, from 50th to 5th — your GP should investigate. Changes in growth trajectory are more significant than absolute position.
Do height percentiles account for ethnicity or family genetics?
The UK90 charts are based on the UK population as a whole. If both parents are tall or short, children naturally track along higher or lower percentiles respectively, which is normal. Your GP considers family height when interpreting growth charts.
What should I do if my child's height seems very different from other children their age?
Book an appointment with your GP or health visitor. They will plot your child's height on the official NHS growth reference charts, check the growth trend, and investigate if there are any underlying causes. Most children with heights at the extremes of the range are simply naturally tall or short.
Ready to take control of your weight loss journey?
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