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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Is 15.8 Stone a Healthy Weight?
15.8 stone is equivalent to approximately 100.5 kilograms. Whether this weight is healthy depends entirely on your height, age, and individual health profile. Using NHS guidelines and the metric to imperial weight conversion standard, we can assess where 15.8 stone falls on the health scale. This guide shows you exactly what this weight means in kilograms, and helps you understand if it's within a healthy range 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.
Healthy Weight Ranges by Height — 15.8 Stone (100.5kg) Context
15.8 stone converts to 100.5 kg exactly. Whether this is healthy depends on your height. Here are three realistic examples using the stone to kg conversion standard:
- At 5ft 4in (163cm): A weight of 100.5kg gives a BMI of 34.1, which falls into the obese category. A healthy range at this height is 47–63kg (7st 5lbs–9st 13lbs).
- At 5ft 9in (175cm): 100.5kg gives a BMI of 32.8, also obese. Healthy weight range is 56–76kg (8st 12lbs–11st 13lbs).
- At 6ft 1in (185cm): 100.5kg gives a BMI of 29.2, which is overweight but not obese. Healthy range is 62–84kg (9st 11lbs–13st 3lbs).
You can check your personal BMI instantly using our free BMI calculator above. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, slightly lower thresholds apply — ask your GP for personalised guidance.
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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 Next Steps
The NHS recommends a healthy BMI of 18.5 to 24.9 for most adults. If 15.8 stone puts you above this range, waist measurement also matters: men above 94cm (37in) and women above 80cm (31.5in) have increased health risk, even at the same weight. Weight is affected by many factors—genetics, age, medications, and lifestyle all play a role. If you'd like support, your GP can discuss your individual health picture and recommend options like lifestyle changes, structured weight loss programmes, or specialist services. Remember, even a 5% reduction in body weight can bring real health benefits.
- 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 15.8 stone in kilograms exactly?
15.8 stone is 100.5 kilograms. To convert kilograms to stone, divide by 6.35029. Conversely, multiply stone by 6.35029 to get kg. Our free weight converter above can do this instantly for any weight you enter.
Is 15.8 stone overweight or obese?
It depends on your height. At 5ft 4in, 15.8 stone is obese (BMI 34.1). At 5ft 9in, it's obese (BMI 32.8). At 6ft 1in, it's overweight (BMI 29.2). Use the BMI calculator on this page with your exact height for your personal result.
What's the healthy weight range for my height at 100.5kg context?
A healthy weight at 5ft 9in is 56–76kg (8st 12lbs–11st 13lbs). At 5ft 4in, it's 47–63kg. At 6ft 1in, it's 62–84kg. Your GP can confirm the healthy range for your individual height and health profile.
Does waist measurement matter if I weigh 15.8 stone?
Yes. Even at the same weight, where fat is stored affects health risk. The NHS recommends measuring your waist: over 94cm (37in) for men and 80cm (31.5in) for women indicates increased risk. Your GP can advise if this matters for you.
What should I do if 15.8 stone is outside my healthy range?
Start by speaking to your GP, who can discuss your individual health, lifestyle factors, and any support available. Options include structured weight loss programmes, NHS weight management services, or registered dietitian advice. Even small changes can make a real difference.
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.