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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19.8kg in Stone — Healthy Weight Context
19.8kg converts to 3 stone and 2.2 pounds (3st 2.2lbs). Whether this is a healthy weight depends entirely on your height. For a young child or someone very short, this weight may be appropriate. For an adult of average height, it would be significantly underweight. This guide shows you how to check if 19.8kg is healthy for your specific height using NHS guidelines, and how to interpret your weight status.
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.
Healthy Weight Ranges at Different Heights
At 19.8kg (3st 2lbs), whether you're in a healthy weight range depends on your height. Use our free BMI calculator above to check your exact BMI instantly, or refer to these examples:
- At 140cm (4ft 7in): 19.8kg gives a BMI of 10.1 — this is underweight (healthy range: 18.5–24.9)
- At 150cm (4ft 11in): 19.8kg gives a BMI of 8.8 — significantly underweight
- At 160cm (5ft 3in): 19.8kg gives a BMI of 7.7 — well below the healthy range
The NHS healthy weight range for any height is a BMI between 18.5 and 24.9. For most adults, 19.8kg would be dangerously low. If you weigh this much, speak to your GP about whether your weight is healthy for you.
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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
If you weigh 19.8kg or are significantly underweight, it's important to discuss this with your GP. Being underweight can indicate nutritional deficiency, metabolic issues, or underlying health conditions. Your GP can assess your individual circumstances and health history.
Additionally, measure your waist circumference for health context: men over 94cm (37in) and women over 80cm (31.5in) have increased health risk, though this applies to overweight ranges. For underweight individuals, the focus is different — your GP will advise on appropriate weight gain and nutrition.
Use our weight converter to track your weight in kg, stone, and pounds as you 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.
What is 19.8kg in stone and pounds?
19.8kg converts to exactly 3 stone and 2.2 pounds (often written as 3st 2.2lbs). In pounds only, 19.8kg equals 43.7 lbs. You can use our free weight converter above to convert between kg, stone, and lbs instantly.
Is 19.8kg a healthy weight for an adult?
For virtually all adults, 19.8kg is significantly underweight and below the NHS healthy range. Healthy weight depends on height, but 19.8kg would only be appropriate for very young children. If you weigh this much as an adult, consult your GP.
How do I calculate my healthy weight range?
Use our BMI calculator on this page to check your BMI instantly. Alternatively, calculate it: BMI = weight (kg) ÷ height (m)². A healthy BMI is 18.5–24.9 according to NHS guidelines. Your GP can provide personalised healthy weight guidance.
What should I do if I'm underweight?
Speak to your GP. Being significantly underweight can indicate medical issues, nutritional deficiency, or eating disorders. Your GP can assess your health, check for underlying causes, and advise on safe weight gain or nutrition support if needed.
How does height affect whether a weight is healthy?
Height is critical — the same weight gives different BMI values at different heights. At 150cm, 19.8kg is dangerously underweight. At 180cm, it would be severely underweight. That's why BMI, not absolute weight, determines health status. Use our BMI calculator to find your personal healthy range.
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.