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 Ideal Body Weight?
There's no single "ideal" body weight that fits everyone — your ideal weight depends on your height, age, genetics, and muscle mass. However, the NHS provides clear guidelines to help you understand what weight range is healthy for you. Rather than chasing a specific number on the scales, focus on achieving a weight that keeps your BMI in the healthy range and supports your overall health and wellbeing. Our free BMI calculator and weight converter make it easy to check where you stand and understand what healthy weight means for your body.
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.
How to Calculate Your Healthy Weight Range
The most practical way to determine your ideal body weight is using your BMI (body mass index) and the NHS healthy weight range for your height. Here's how:
- Calculate your BMI: Divide your weight in kilograms by your height in metres squared. A healthy BMI for most UK adults is 18.5 to 24.9.
- Work backwards to weight: Multiply 18.5 by your height squared for the lower healthy weight, and 24.9 by the same figure for the upper range.
- Example: For someone 1.75m tall, the healthy weight range is approximately 56–76 kg (8st 11lbs to 12st 0lbs).
The NHS also recommends checking your waist circumference — for men over 94cm or women over 80cm indicates increased health risk, regardless of BMI. Use our free BMI calculator above to instantly find your personal healthy range based on your exact height.
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.
Beyond BMI: What Else Matters for Ideal Weight
BMI is a useful starting point but doesn't tell the whole story. Muscle mass, bone density, and where you carry fat all affect your actual health risk. An athletic person with high muscle may have a high BMI but low body fat, while someone with a "healthy" BMI might have poor fitness. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds (18.5–22.9 for healthy weight) because these groups face higher health risks at the same BMI. Your GP can provide personalised advice about your ideal weight based on your individual health, medical history, and fitness level — this is more valuable than any formula.
- 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's the difference between ideal weight and healthy weight?
Ideal weight is your personal target weight based on your goals and body type. Healthy weight is the evidence-based range recommended by NHS guidelines for your height. The healthy range (BMI 18.5–24.9) is more important than chasing a specific "ideal" number. Your GP can help you set a realistic healthy weight goal.
Can I use weight converter tools to check if my weight is healthy?
Yes. Our free weight converter helps you switch between kg, stone, and pounds, making it easier to understand your weight in the units you're familiar with. Then use our BMI calculator to check if that weight falls in the healthy range for your height.
Does ideal body weight change with age?
Your BMI healthy range doesn't change with age, but muscle mass naturally decreases with age, and your metabolism may slow. This means you may need fewer calories to maintain the same weight. Older adults should focus on staying active and maintaining muscle rather than reaching a specific weight number.
Are the Devine and Robinson formulas accurate for UK adults?
These formulas are reference guides only — they estimate ideal weight based on height and frame size. The NHS BMI range is more reliable and evidence-based. Results vary widely depending on genetics, muscle mass, and bone structure, so formulas shouldn't be used alone. Your GP is the best source for personalised guidance.
How does weight management fit into reaching ideal body weight?
Reaching and maintaining a healthy weight usually involves gradual changes — the NHS recommends losing no more than 0.5–1 kg per week for sustainable results. Weight management includes balanced nutrition, regular activity, and sometimes medical support. Our progress tracker helps you log your journey and stay motivated.
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.