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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12.4 kg in Stone — Quick Conversion
12.4 kilograms is equivalent to 1 stone and 13.5 pounds (or 1st 13.5lbs). This weight measurement is commonly used in the UK, where stone remains the standard unit for body weight despite most medical measurements being recorded in kilograms on NHS systems. Whether you're checking a weight in metric or imperial measurements, understanding how to convert kilograms to stone quickly is helpful for tracking health and fitness goals. Use our free weight converter above to switch between kg, stone, and pounds instantly.
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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.
Conversion Formula and Reference Table
To convert 12.4 kg to stone, divide the kilogram value by 6.35029. The standard kg to stone conversion formula is: kilograms ÷ 6.35029 = stone. For 12.4 kg, this gives 1.95 stone, which breaks down into 1 stone and 13.5 pounds when expressing weight in stone and pounds format.
Here are nearby values to help you understand the conversion scale:
- 10 kg = 1st 7.3lbs
- 11 kg = 1st 9.6lbs
- 12 kg = 1st 11.9lbs
- 12.4 kg = 1st 13.5lbs
- 13 kg = 2st 0.3lbs
- 14 kg = 2st 2.6lbs
- 15 kg = 2st 5lbs
If you need to reverse the calculation, stone to kg conversion uses: stone × 6.35029 = kilograms.
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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.
BMI and Health Context at 12.4 kg
At 12.4 kg, BMI depends entirely on height. For context, a typical adult height in the UK is around 168 cm (5ft 6in). At this height, 12.4 kg would give a BMI of approximately 4.4, which is significantly underweight and well below NHS healthy weight guidelines (BMI 18.5–24.9). For an adult of average UK height, this weight would be unusually low. Calculate your personal BMI using our free BMI calculator on this page to see where your weight falls relative to NHS guidelines for your specific height and build.
- 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 12.4 kg in stone and pounds?
12.4 kg equals 1 stone and 13.5 pounds. To express this more precisely in decimal form, it's 1.95 stone. This conversion uses the standard factor of 1 stone = 6.35029 kilograms, which is the exact conversion rate used by UK healthcare and fitness professionals.
How do I convert kilograms to stone manually?
Divide the kilogram amount by 6.35029 to get stone. For example: 12.4 ÷ 6.35029 = 1.95 stone. If you want stone and pounds, multiply the decimal portion by 14 (since 1 stone = 14 pounds). Our free weight converter above makes this instant and removes calculation errors.
Is 12.4 kg a healthy weight for an adult?
12.4 kg is significantly underweight for any adult. Healthy weight depends on height—use the BMI calculator on this page to check your personal BMI. For most UK adults, a healthy weight falls in the 50–90 kg range, though this varies widely by height and build. Consult your GP if you have concerns about low body weight.
Why does the UK use stone instead of kilograms for body weight?
Tradition and cultural preference. Most UK adults and healthcare workers use stone for body weight discussions, even though NHS clinical records are maintained in kilograms. The UK is unique in this—most other countries use only kilograms. Both measurements are equally valid; it's simply what feels familiar to British users.
How accurate is the kg to stone conversion?
The conversion factor 1 stone = 6.35029 kg is exact and internationally standardised. All conversions using this factor are accurate to decimal places. Minor variations may appear due to rounding, but for practical health purposes, the conversion is precise. Use our weight converter tool for instant, accurate conversions.
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.