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 the Best Body Weight for You?
The "best" body weight isn't a single number — it depends on your height, age, muscle mass, and individual health. The NHS provides healthy weight ranges based on BMI, and for most UK adults, a BMI between 18.5 and 24.9 is considered healthy. However, factors like ethnicity, fitness level, and personal health conditions all play a role. Use our free BMI calculator above to find where your current weight sits, and discover what a healthy weight range means for your specific height.
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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 Your Height Determines Healthy Weight Range
Your height is the primary factor in calculating healthy body weight. The NHS uses BMI (Body Mass Index) — a calculation based on your weight and height squared — to categorise whether a weight is healthy, overweight, or obese. For example, at 5ft 8in (173cm), the healthy weight range is approximately 55–74kg (8st 8lbs to 11st 8lbs). At 5ft 4in (163cm), the healthy range drops to 48–64kg (7st 7lbs to 10st 1lb). These ranges account for natural variation in frame size and muscle distribution.
Our free weight converter tool lets you switch between kg, stone, and pounds instantly, so you can see your target weight in whichever measurement you prefer. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends slightly lower thresholds because these groups face higher health risks at lower BMI levels. Your GP can give personalised guidance based on your ethnic background and individual circumstances.
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.
Factors Beyond BMI — What Really Matters
BMI has important limitations. It doesn't distinguish between muscle and fat — athletes may have a high BMI but low body fat — and it doesn't account for where fat is stored (visceral fat around the organs is more risky than subcutaneous fat). Waist circumference matters too: the NHS recommends keeping waist measurements under 94cm (37in) for men and 80cm (31.5in) for women. Age, fitness level, medical history, and medications all influence what constitutes a healthy weight for you personally.
Rather than chasing a single "ideal" number, focus on sustainable habits: regular movement, balanced nutrition, and stress management. Even a 5–10% reduction in body weight can significantly improve health markers like blood pressure and blood sugar levels. Your GP can assess your individual health and suggest whether any interventions — lifestyle changes, weight loss support, or in some cases prescription treatments — might be appropriate.
- 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 healthy weight range for my height?
Use the NHS BMI categories: a BMI of 18.5–24.9 is healthy for most UK adults. Calculate your specific range using our free BMI calculator above — it accounts for your exact height and gives you the target weight in kg, stone, and pounds. For South Asian, Chinese, Black African, or Caribbean adults, lower thresholds apply.
Is BMI the only measure of healthy body weight?
No. BMI is useful but has limitations — it doesn't distinguish muscle from fat. Waist circumference is equally important: under 94cm for men, under 80cm for women indicates lower health risk. Body composition, fitness level, and overall health matter too. Your GP can provide personalised assessment.
Does my ethnic background affect my healthy weight?
Yes. The NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean heritage because these groups face higher risk of type 2 diabetes and heart disease at lower BMI levels. Your GP can advise on thresholds relevant to you.
Can I lose weight sustainably without it being my "ideal" weight?
Absolutely. Even a 5–10% loss of body weight improves blood pressure, blood sugar, and joint health. Focus on sustainable habits rather than a specific target number. Try our free progress tracker to log changes over time and celebrate real health improvements, not just scale numbers.
What if I can't reach the "healthy" BMI range?
That's okay. Health is multifactorial. Some people have medical conditions or medications affecting weight. Work with your GP on realistic, personalised goals. If weight loss support is needed, options range from lifestyle programmes to, in some cases, prescription weight loss treatments — all determined by your individual circumstances.
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.