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
Is 9.8kg in Stone a Healthy Weight?
9.8kg converts to 1 stone 8.3 lbs (or approximately 21.6 lbs). Whether this weight is healthy entirely depends on your height. A weight of 9.8kg would be very light for most adults — it's typically healthy only for young children or infants. For context, the average UK adult weighs between 70–90kg. If you're an adult, use our free BMI calculator above to check your personal health status, which combines your weight with your height to give you a meaningful picture of your weight category.
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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
A healthy weight range depends entirely on height. Here are three real-world examples of how 9.8kg would be interpreted:
- 5ft 0in (152cm): Healthy BMI range is 47–64kg. At 9.8kg, this would be significantly underweight.
- 5ft 4in (163cm): Healthy BMI range is 49–66kg. At 9.8kg, this would be severely underweight.
- 5ft 10in (178cm): Healthy BMI range is 57–76kg. At 9.8kg, this would be dangerously underweight.
According to NHS guidelines, a healthy BMI sits between 18.5 and 24.9 for most UK adults. Your personal healthy weight range can be calculated by combining your height and weight — use our weight converter above to confirm your weight in different units, then check it against NHS BMI thresholds for your height.
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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
If you're an adult weighing 9.8kg, this would indicate a serious health concern requiring urgent GP assessment. Severe underweight status can cause malnutrition, weakened immunity, bone loss, and other complications.
If you're concerned about your weight — whether you think you're underweight, overweight, or unsure — your GP is the best starting point. They can assess your individual health status, consider your medical history, and offer personalised guidance. Waist measurement also matters: NHS guidance suggests increased health risk if waist circumference exceeds 94cm for men or 80cm for women. Track your progress with our free progress tracker to monitor changes over time.
- 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 9.8kg to stone and pounds precisely?
Divide 9.8 by 6.35 to get stone (1.54 stone), then multiply the decimal by 14 to get pounds (7.6 lbs). So 9.8kg equals approximately 1 stone 7.6 lbs. Our weight converter above does this instantly for you.
Is 9.8kg a healthy weight for an adult?
No. For virtually all adult heights, 9.8kg would be dangerously underweight and would require urgent medical assessment. This weight might be appropriate for a very young child, but for adults it indicates a serious health concern.
What BMI does 9.8kg give me?
BMI depends on height. At 9.8kg, even for very short adults, BMI would fall in the severely underweight category (below 15). Use our free BMI calculator on this page to calculate your specific BMI by entering your height and weight.
What should I do if I'm significantly underweight?
See your GP for a full health assessment. Severe underweight status can affect bone density, immune function, and overall health. Your GP can identify underlying causes and refer you to appropriate support, which might include a dietitian or specialist.
How does waist measurement relate to weight health?
Waist circumference is important independent of weight. NHS guidance recommends measuring your waist — increased health risk is indicated above 94cm for men or 80cm for women, regardless of BMI category.
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.