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
How Weight and Height Affect Your Health
Your weight and height are fundamental to assessing your overall health risk. Together, they determine your BMI (body mass index), which is the primary screening tool used by the NHS to identify whether an adult is at a healthy weight. Understanding the relationship between these two measurements helps you establish realistic health goals and access appropriate support if needed. This guide explains how health professionals in the UK use weight and height together, what healthy ranges look like, and how to use free tools to track your personal metrics.
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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 Weight and Height Work Together
Weight and height are inseparable when assessing health risk. The NHS uses BMI—calculated by dividing your weight in kilograms by your height in metres squared—to screen for conditions linked to excess weight, including type 2 diabetes, high blood pressure, and heart disease.
- At the same weight, taller people have a lower BMI than shorter people
- At the same height, heavier people have a higher BMI than lighter people
- A healthy BMI range for UK adults is 18.5 to 24.9 (or 18.5 to 22.9 for South Asian, Chinese, Black African, and Black Caribbean adults)
- BMI categories apply from age 18 onwards—children use age and sex-specific growth charts instead
Your GP can use weight and height measurements alongside other factors—such as waist circumference, family history, and lifestyle—to give you personalised health advice. Use our free BMI calculator above to check your personal BMI instantly based on your weight and height.
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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.
Healthy Weight Ranges and Your Personal Metrics
A healthy weight range depends entirely on your height. The NHS provides weight management guidance based on BMI thresholds that apply across the UK population. For example, someone who is 1.73m (5ft 8in) tall has a healthy weight range of approximately 55–74 kg (8st 9lbs to 11st 9lbs). Someone who is 1.60m (5ft 3in) tall has a healthy weight range of approximately 47–64 kg (7st 6lbs to 10st 1lb).
Rather than comparing yourself to others, focus on where you sit within your own healthy range. Track your progress using our free progress tracker, and use our weight converter to compare your weight across kg, stone, and pounds for easy reference with UK health charts.
- 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 healthy weight range using my height?
Multiply your height in metres by itself, then multiply by 18.5 (lower bound) and 24.9 (upper bound). For example, at 1.70m: lower bound = 18.5 × (1.70)² = 53.4 kg; upper bound = 24.9 × (1.70)² = 71.9 kg. Our free BMI calculator does this automatically.
Does height affect how weight loss medication works?
Height affects BMI eligibility thresholds for prescription weight loss treatment like Mounjaro or Wegovy, which are prescribed based on BMI and health conditions. Clinical trial results (average 15–clinically studied weight loss) are similar across different heights when medications are used with diet and activity changes.
Why does the NHS use both weight and height instead of just weight?
Weight alone doesn't indicate health risk—a person who weighs 80 kg might be muscular and healthy, or carry excess fat. Height accounts for this variation. BMI uses both measurements to estimate body composition risk and identify who may benefit from health support.
Are there ethnic differences in healthy weight ranges for my height?
Yes. The NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean heritage because these groups face higher health risks at lower BMI levels. If you're in these groups, a healthy BMI starts at 18.5 but extends only to 22.9 rather than 24.9.
Can I use weight and height alone to know if I'm healthy?
BMI is a useful screening tool but has limitations—it doesn't distinguish between muscle and fat. Waist circumference, family history, activity level, and blood pressure are also important. Your GP can assess your individual health risk based on the full picture, not BMI alone.
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.