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
What is 15.8 Stone in Kilograms?
15.8 stone is equal to approximately 100.4 kg. This weight conversion uses the standard metric to imperial weight conversion formula widely used in the UK. If you're tracking your weight for health reasons or comparing measurements between UK and metric systems, understanding how to convert stone to kg is straightforward. Use our free weight converter above to switch between stone, pounds, and kilograms instantly for any value.
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.
Stone to Kg Conversion Table and Formula
15.8 stone = 100.4 kg
To convert stone to kilograms, multiply the stone value by 6.35029. The formula is: stone × 6.35029 = kg. For 15.8 stone: 15.8 × 6.35029 = 100.36 kg (rounded to 100.4 kg).
Here are nearby values for reference:
- 15.2 stone = 96.5 kg
- 15.4 stone = 97.7 kg
- 15.6 stone = 98.9 kg
- 15.8 stone = 100.4 kg
- 16.0 stone = 101.6 kg
- 16.2 stone = 102.8 kg
- 16.4 stone = 104.1 kg
For reverse conversions, use the kilogram to stone conversion: divide kg by 6.35029 to get stone.
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.
BMI and Health Context at 15.8 Stone
At 15.8 stone (100.4 kg), your BMI depends on your height. Using our free BMI calculator, you can determine your personal BMI instantly. For example, at an average UK male height of 5ft 9in (175cm), a weight of 100.4 kg gives a BMI of approximately 32.8, which falls in the obese category according to NHS guidelines. For an average UK female height of 5ft 4in (163cm), the same weight gives a BMI of around 37.8. The healthy weight range for these heights is significantly lower, and speaking with your GP can help determine personalised health goals.
- 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 15.8 stone to kilograms?
Multiply 15.8 by 6.35029. This gives 100.36 kg, rounded to 100.4 kg. You can use our free weight converter above for instant conversions between stone, pounds, and kilograms without a UK pharmacy calculation.
Is 15.8 stone a healthy weight?
Whether 15.8 stone is healthy depends on your height, age, and overall health. Use the BMI calculator on this page to check your BMI. The NHS considers a BMI of 18.5–24.9 healthy for most adults. If your BMI is higher, your GP can discuss personalised health goals and support options.
What is 15.8 stone in pounds?
15.8 stone equals 221.2 pounds. Since one stone equals exactly 14 pounds, multiply 15.8 × 14 = 221.2 lbs. Our weight converter above can convert between all units instantly.
What is the healthy weight range for my height?
The healthy weight range varies by height. For example, at 5ft 9in, the healthy range is approximately 55–75 kg. Calculate your personal healthy weight range using our free BMI calculator, which uses NHS guidelines and accounts for your specific height.
Why do UK adults use stone instead of kilograms?
The UK has traditionally used imperial measurements including stone for body weight, while most of Europe uses metric kilograms. The NHS uses kg clinically, but many UK individuals, fitness programmes, and weight management services still refer to stone and pounds in everyday conversation.
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.