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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Ideal Body Weight For Height
Your ideal body weight depends on your height, age, sex, and body composition — there's no single "perfect" weight that applies to everyone. The NHS recommends using BMI (body mass index) as a screening tool, alongside waist measurement, to assess whether your weight is healthy for your height. This guide explains how to calculate your ideal weight range, the limitations of weight-based health assessment, and how to use our free BMI calculator and weight converter to find where you stand. Individual genetics, muscle mass, and overall fitness all play a role in what's healthy for you personally.
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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 to Calculate Your Ideal Weight Range for Your Height
The Devine Formula and Robinson Formula are two commonly used equations to estimate ideal body weight based on height. For men using the Devine Formula, start with 50 kg and add 2.3 kg for each inch over 5 feet. For women, start with 45.5 kg and add 2.3 kg per inch over 5 feet. However, these are reference calculations only — your actual ideal weight depends on factors like muscle mass, bone density, and frame size.
A more practical approach is to use your healthy weight range based on BMI. The NHS recommends a BMI between 18.5 and 24.9 for most adults. To find your healthy range, calculate the weight at BMI 18.5 and BMI 24.9 for your height. For example, at 1.73m (5ft 8in), the healthy range is approximately 55–74 kg (8st 8lbs to 11st 9lbs). Use our free BMI calculator above to find your personal healthy weight range instantly, and our weight converter to switch between kg, stone, and pounds.
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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.
Why BMI Alone Isn't the Complete Picture
BMI is a useful screening tool but has important limitations. It doesn't distinguish between muscle and fat — an athlete with high muscle mass may have a high BMI but low body fat percentage. BMI also doesn't account for where fat is stored; excess weight around the stomach carries greater health risk than weight distributed elsewhere. For these reasons, the NHS also recommends measuring waist circumference alongside BMI. Men should aim for under 94 cm (37 inches), and women under 80 cm (31.5 inches). If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends slightly lower thresholds due to higher health risks at equivalent BMI levels. Your GP can provide personalised guidance on what a healthy weight means for your individual health.
- 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 someone 5ft 6in tall?
At 5ft 6in (168 cm), a healthy BMI range of 18.5–24.9 corresponds to approximately 52–70 kg (8st 2lbs to 11st). Your ideal weight within this range depends on your age, sex, muscle mass, and overall health. Use our BMI calculator to find your exact range and health assessment.
Does ideal body weight change with age?
Yes. As we age, muscle mass naturally decreases and body composition changes. Older adults may maintain a slightly higher BMI without increased health risk compared to younger adults. Your GP can advise on what's healthy for your age and individual circumstances.
Can I use the Devine Formula to find my ideal weight?
The Devine Formula is a reference calculation, but it's not personalised. It estimates ideal weight as 50 kg + 2.3 kg per inch over 5 feet for men, and 45.5 kg + 2.3 kg per inch for women. However, BMI-based healthy ranges aligned with NHS guidance are more clinically useful for assessing health.
What's the difference between "ideal weight" and "healthy weight"?
Ideal weight is a target number based on formulas. Healthy weight is a range (based on BMI 18.5–24.9) that takes into account your height and aligns with NHS health guidance. Healthy weight is more accurate because it accounts for natural variation in body composition and frame size.
How does muscle mass affect ideal body weight?
Muscle weighs more than fat at the same volume. Someone with high muscle mass may weigh more than BMI suggests is "ideal" but have excellent health. This is why BMI should always be considered alongside waist measurement and overall fitness, not as the sole measure of health.
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.