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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8.7 Stone in kg — What's a Healthy Weight?
8.7 stone converts to approximately 55.2 kg. Whether this weight is healthy for you depends entirely on your height, age, and overall health. Using NHS guidelines and our free BMI calculator, you can check if 55.2 kg falls within a healthy weight range for your individual measurements. This guide explains how to assess your weight in kg, understand healthy ranges, and what action to take if you're outside the recommended bracket — all without judgment, just practical health information.
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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.
Healthy Weight Ranges at Different Heights
To find out if 55.2 kg is healthy, you need to calculate your BMI (Body Mass Index) using your height. The NHS provides standard BMI categories: a healthy BMI is between 18.5 and 24.9. Here are three real-world examples showing how the same weight of 8.7 stone (55.2 kg) can be healthy or overweight depending on height:
- At 1.60m (5ft 3in): 55.2 kg gives a BMI of 21.6 — healthy weight range.
- At 1.73m (5ft 8in): 55.2 kg gives a BMI of 18.5 — at the lower edge of healthy weight.
- At 1.85m (6ft 1in): 55.2 kg gives a BMI of 16.1 — underweight by NHS standards.
Use our weight converter to switch between kg to stone and calculate your personal BMI instantly. Remember, BMI does not account for muscle mass or fat distribution, so it's a screening tool rather than a definitive health measure.
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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.
NHS Guidance and What to Do Next
If your BMI based on 55.2 kg and your height falls outside the healthy 18.5–24.9 range, the NHS recommends speaking to your GP for personalised advice. Additionally, waist measurement matters: the NHS suggests measuring around your natural waist to check for excess abdominal fat, which carries health risks independent of BMI. Men should aim for under 94cm (37 inches), women under 80cm (31.5 inches). If you need to manage your weight, sustainable approaches include a balanced diet with a moderate calorie deficit, regular physical activity, and lifestyle adjustments. Our free progress tracker can help you log changes over time and stay motivated on your health journey.
- 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.
How do I convert 8.7 stone to kilograms?
8.7 stone multiplied by 6.35 equals approximately 55.2 kg. You can use the standard stone to kg conversion factor of 6.35, or use our free weight converter above for gradual improvement across all units.
Is 55.2 kg a healthy weight?
It depends on your height. At 5ft 3in (1.60m), 55.2 kg is healthy. At 5ft 8in (1.73m), it's on the lower edge of healthy. At 6ft 1in (1.85m), it would be underweight. Use our BMI calculator to check your personal healthy range.
What is a healthy BMI according to the NHS?
The NHS defines a healthy BMI as 18.5 to 24.9 for most UK adults. If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a lower threshold of 18.5 to 22.9 due to higher health risks at lower BMI levels.
How many kg is one stone?
One stone equals exactly 6.35 kg. Therefore, to convert any weight in stone to kilograms, multiply the stone figure by 6.35. This kilogram to stone conversion works in both directions using the same factor.
What should I do if my weight is outside the healthy range?
Speak to your GP for personalised advice. They can assess your overall health, discuss sustainable weight management options, and recommend lifestyle changes or referral to specialist services if appropriate. Your GP can also check waist circumference and other health markers.
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.