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 My Appropriate Weight?
Your appropriate weight depends on your height, age, sex, and overall health — not a single number. The NHS uses BMI (Body Mass Index) as the primary screening tool to define healthy weight ranges for UK adults. A healthy BMI is between 18.5 and 24.9, though ethnicity-adjusted thresholds apply for people of South Asian, Chinese, Black African, and Black Caribbean heritage. Your GP can assess what's appropriate for you personally, as factors like muscle mass, medical history, and family genetics all play a role. Use our free BMI calculator above to check where you currently fall, and our weight converter to see your weight across different UK measurements.
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
Your healthy weight range is determined by your height and target BMI. The calculation is straightforward:
- Multiply your height in metres by itself (height²)
- Multiply this by 18.5 (lower healthy BMI limit)
- Multiply by 24.9 (upper healthy BMI limit)
For example, if you're 1.73m tall (5ft 8in), your healthy weight range is approximately 55–75 kg (8st 8lbs–11st 11lbs). This is NHS guidance for general adult populations. However, for adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds apply — a healthy BMI range is 18.5 to 22.9 instead. This is because these groups face higher health risks from type 2 diabetes and cardiovascular disease at lower BMI levels. Your weight converter tool can help you switch between kg, stone, and pounds instantly for any height or weight combination.
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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.
Factors Beyond BMI That Matter
BMI is a useful screening tool, but it has important limitations. It doesn't distinguish between muscle and fat — so an athlete with high muscle mass might have a BMI in the "overweight" range despite having low body fat. It also doesn't account for where fat is stored; fat around the belly (visceral fat) carries greater health risk than fat stored elsewhere. The NHS therefore recommends also measuring your waist circumference: men should aim for under 94cm (37in), women under 80cm (31.5in). Age, hormonal health, medical conditions like thyroid disease, and medications you take all influence your appropriate weight. Your GP or a registered dietitian can provide personalised guidance that goes beyond BMI, considering your complete health picture and individual circumstances.
- 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 considered a healthy weight in the UK?
According to NHS guidelines, a healthy BMI is between 18.5 and 24.9. For most UK adults, this translates to a healthy weight range based on your height. For example, at 5ft 8in (1.73m), a healthy weight is approximately 55–75 kg (8st 8lbs–11st 11lbs). Lower BMI thresholds apply for South Asian, Black African, and Chinese adults.
How do I calculate my ideal weight for my height?
Multiply your height in metres by itself, then multiply by 18.5 (lower limit) and 24.9 (upper limit) to find your healthy weight range in kg. For example: at 1.70m, healthy weight is roughly 53–72 kg. Our free BMI calculator does this instantly — just enter your height and current weight.
Does everyone need to be within the BMI healthy range?
BMI is a screening tool, not a diagnosis. Some people with high muscle mass may have a higher BMI but good health. Others with metabolic conditions may need a different target. Your GP can assess whether your current weight is appropriate for your individual health needs, medical history, and circumstances.
What if I'm significantly above my healthy weight range?
Even modest weight loss — 5–10% of body weight — can improve blood pressure, blood sugar control, and reduce joint stress. The NHS recommends losing weight gradually at 0.5–1 kg per week. Your GP can discuss options including behaviour change programmes, diet support, or referral to specialist weight management services.
Are weight ranges different for different ages?
The BMI healthy range (18.5–24.9) applies to all adults aged 18–65. For older adults, slightly higher BMI may sometimes be protective, and for children, age-adjusted growth charts are used instead. Your GP can advise on age-specific guidance for your situation.
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.