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
What's the Right Weight for Your Height and Age?
There's no single "perfect" weight that applies to everyone — it depends on your height, age, sex, and body composition. However, the NHS provides clear healthy weight ranges based on BMI (body mass index) that help you understand whether your current weight falls within a safe, healthy zone. In the UK, we use stone and kilograms to measure weight, and your GP can give you personalised guidance based on your individual health. Our free BMI calculator above can help you find out where you stand right now.
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 Healthy Weight Guidance for UK Adults
The NHS recommends a healthy BMI range of 18.5 to 24.9 for most UK adults. This translates to different weights depending on your height. For example, an adult who is 5ft 8in (173cm) tall would have a healthy weight range of approximately 55–74kg (8st 8lbs to 11st 10lbs). However, age and ethnicity matter. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds: a healthy BMI of 18.5 to 22.9. Weight loss guidance from NICE emphasises that even a modest 5–10% reduction in body weight brings measurable health benefits, regardless of your starting point. Use our free BMI calculator to discover your personal BMI instantly.
- Healthy BMI: 18.5–24.9 (most populations)
- Healthy BMI: 18.5–22.9 (South Asian, Chinese, Black African/Caribbean)
- Weight management is gradual, sustainable loss of 0.5–1kg per week
- Individual health factors always matter more than the number on the scales
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.
Using UK Tools and Getting GP Support
Finding your right weight is easier with practical tools designed for UK measurements. Our free weight converter helps you switch between kilograms, stone, and pounds — the units you actually use in daily life in the UK. However, BMI is just one part of the picture. Your waist circumference also matters: the NHS flags increased health risk at over 94cm (37in) for men and 80cm (31.5in) for women. Rather than chasing a specific number, focus on sustainable lifestyle changes: balanced nutrition, regular physical activity, and adequate sleep. Your GP can assess your individual health and recommend the right approach for you, whether that's self-managed changes or support from NHS weight management services.
- 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 the ideal weight for my height and age?
There is no single ideal weight — it depends on your individual body composition, muscle mass, and health. The NHS uses BMI to define healthy ranges: 18.5–24.9 for most adults, or 18.5–22.9 for those of South Asian, Chinese, or Black African/Caribbean heritage. Use our BMI calculator to find your healthy range based on your specific height.
Does age affect what a healthy weight should be?
Yes. Muscle mass naturally declines with age, so the same weight may look and feel different at 25 versus 65. Additionally, health risk thresholds can shift in older age. Your GP can provide age-specific guidance. BMI is one tool, but waist circumference and overall fitness matter too.
How much weight should I aim to lose per week?
The NHS recommends losing 0.5–1kg (1–2 lbs) per week for sustainable, healthy weight loss. This typically requires a calorie deficit of around 500 kcal per day. Faster weight loss is possible with medical support but increases the risk of muscle loss and nutritional deficiency.
What if my BMI says I'm overweight but I feel healthy?
BMI does not account for muscle mass, bone density, or where fat is stored. Athletes may have a high BMI but low body fat. However, if your BMI is above 25, your GP can assess your overall health — including blood pressure, blood sugar, cholesterol, and waist circumference — to give you personalised advice.
Should I use online weight loss calculators or speak to my GP?
Both are valuable. Use our free tools to understand your BMI and project potential weight loss. However, your GP can assess your individual health, identify any underlying conditions, and recommend the right support for you — whether that's lifestyle changes, NHS weight management services, or prescription options.
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.