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
6.3 Kg In Stone — Is This A Healthy Weight?
6.3 kg converts to 0 stone 9.9 pounds (or approximately 14 lbs). Whether this weight is healthy depends entirely on your height — it's a very light weight that would typically indicate underweight status for most adults, unless you're a young child or very short. Using the NHS BMI formula and our free BMI calculator, we can check if this weight falls within a healthy range for your specific height. Read on to see concrete examples and NHS guidance on what constitutes a healthy weight.
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 By Height — Examples
At 6.3 kg, your weight is significantly below the healthy range for virtually all adults. To understand if this applies to you, here are three realistic height examples showing what a healthy weight looks like:
- If you're 150 cm (4ft 11in): Healthy weight range is 41–52 kg. At 6.3 kg, you would be severely underweight (BMI 2.8).
- If you're 160 cm (5ft 3in): Healthy weight range is 47–63 kg. At 6.3 kg, you would be severely underweight (BMI 2.5).
- If you're 170 cm (5ft 7in): Healthy weight range is 53–72 kg. At 6.3 kg, you would be severely underweight (BMI 2.2).
Use our free BMI calculator above to enter your actual height and see where 6.3 kg places you specifically. Even at the shortest adult heights, this weight would be dangerously low.
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.
NHS Guidance & What To Do If Underweight
The NHS defines healthy BMI as 18.5 to 24.9 for most UK adults. A weight of 6.3 kg would result in a BMI well below 18.5, classifying as underweight. Being significantly underweight carries health risks including weakened immune function, bone density loss, and nutritional deficiencies. If you're currently at or near this weight, contact your GP who can assess your overall health, check for underlying causes, and refer you to a dietitian if needed. Waist measurement and general health checks are also important — weight alone doesn't tell the whole story.
- 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 6.3 kg in stone and pounds?
6.3 kg equals 0 stone 9.9 pounds (approximately 14 lbs). To convert kilograms to stone, divide the kg figure by 6.35 — this gives you the stone equivalent. You can also use our free weight converter above to switch between kg, stone, and pounds instantly.
Is 6.3 kg a healthy weight for an adult?
No. At 6.3 kg, this weight would be severely underweight for any adult, regardless of height. A healthy weight range depends on your height and is calculated using BMI — the NHS healthy BMI range is 18.5 to 24.9. Even the shortest adult would need to weigh significantly more than 6.3 kg to be in a healthy range.
Could 6.3 kg be healthy for a child?
It depends on the child's age. Very young infants (newborns to 6 months) can weigh around 6–8 kg, which is normal. However, for older children, this weight would be concerning. Always use NHS growth charts for children, not adult BMI categories. Contact your health visitor or GP if you have concerns about a child's weight.
What should I do if I weigh around this amount as an adult?
If you're an adult weighing significantly below a healthy BMI range, contact your GP. Being underweight can indicate nutritional deficiencies, illness, or other health issues. Your GP can assess you properly, run tests if needed, and refer you to a dietitian for personalised guidance on safe, healthy weight gain.
How do I know my healthy weight range?
Your healthy weight range depends on your height. Use our free BMI calculator above to enter your height — it will show your healthy weight range instantly. The NHS defines healthy BMI as 18.5 to 24.9. For South Asian, Chinese, Black African, or Black Caribbean adults, the threshold is slightly lower (18.5 to 22.9).
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.