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 Is Your Perfect Body Weight?
There's no single "perfect" body weight — what matters is finding a healthy weight that's right for your individual circumstances. In the UK, the NHS uses BMI (body mass index) and health markers rather than an ideal number on the scales. Your perfect body weight depends on your height, age, genetics, muscle mass, and overall health. The goal is sustainable weight management that reduces health risks and improves your quality of life, not chasing an arbitrary target. Our free BMI calculator can help you discover what a healthy weight range looks like for your specific height and build.
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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.
Finding Your Healthy Weight Range with UK Health Guidance
The NHS recommends using BMI as a screening tool to determine whether your weight falls within a healthy range. For most UK adults, a healthy BMI is between 18.5 and 24.9. However, BMI is not the whole picture — it doesn't account for muscle mass, bone density, or where fat is stored on your body.
- Height matters significantly: A person 5ft 4in (163cm) with a healthy BMI might weigh around 47–63kg (7st 5lbs to 10st). Someone 5ft 10in (178cm) might weigh 54–78kg (8st 6lbs to 12st 3lbs).
- Ethnicity affects thresholds: For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds (18.5–22.9 for healthy weight).
- Age and life stage: What's perfect for a 25-year-old differs from what's healthy for a 65-year-old. Muscle naturally declines with age.
- Health markers matter more than the number: Blood pressure, cholesterol, blood sugar, and fitness levels are often better indicators of health than weight alone.
Use our free weight converter to check where your current weight sits in stone and kilograms, then compare it against the healthy range for your height using our BMI calculator.
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.
NHS Guidance and Moving Beyond "Perfect"
The concept of a "perfect" body weight can be harmful — it often ties weight to appearance rather than health outcomes. The NHS focuses on sustainable weight management for health improvement, not reaching an arbitrary target.
What the NHS actually recommends: losing weight at a sustainable rate of 0.5–1kg per week if weight loss is needed, combining dietary changes with physical activity. Even a 5–10% reduction in body weight can significantly improve blood pressure, reduce type 2 diabetes risk, and ease joint strain. Your GP can assess your individual health situation and advise whether weight loss would benefit you. Rather than chasing perfection, focus on consistency, health markers, and how you feel day-to-day. Track your progress with our free progress tracker to monitor real health improvements alongside any weight changes.
- 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 perfect body weight for me?
There's no universal perfect weight. Your healthy weight range depends on your height, age, genetics, and health conditions. Use our BMI calculator to find the healthy range for your specific height. For most UK adults, a BMI between 18.5–24.9 is considered healthy. Your GP can assess whether your current weight is healthy for you individually.
How do I calculate my healthy weight range?
The NHS uses BMI as a screening tool. To find your healthy weight range, you need your height. The healthy BMI range is 18.5–24.9, which converts to different weights depending on height. For example, at 5ft 8in (173cm), a healthy weight is roughly 55–74kg (8st 10lbs to 11st 8lbs). Our free BMI calculator does this instantly.
Is BMI the only thing that matters for body weight?
No. BMI is a useful screening tool but has significant limitations. It doesn't distinguish between muscle and fat, doesn't account for where fat is stored (waist circumference matters), and may not be accurate for athletes or elderly people. Blood pressure, cholesterol, fitness level, and how you feel are equally important health markers.
What does the NHS say about ideal body weight?
The NHS doesn't focus on a single ideal weight. Instead, it recommends achieving a healthy weight range (BMI 18.5–24.9) and maintaining healthy lifestyle habits. For adults of certain ethnic backgrounds, lower thresholds apply. The NHS emphasises sustainable weight loss of 0.5–1kg per week if weight loss is needed, alongside diet and activity changes.
How can I manage my weight effectively in the UK?
Start with your GP, who can assess your individual health and recommend whether weight loss would benefit you. The NHS offers free resources including the NHS Weight Loss Plan. Consider using our free weight converter and BMI calculator to understand your current position, then track progress with our progress tracker. Combine realistic dietary changes with regular physical activity for sustainable results.
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.