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 6 Stone 5 in Kilograms?
6 stone 5 pounds converts to approximately 40.4 kilograms. This is a straightforward metric conversion using the standard UK-to-metric formula. If you're tracking your weight in different units for health reasons, medical appointments, or using online health calculators, understanding how to convert between stone and kilograms is useful. Our free weight converter above makes instant conversions easy, and we've also included BMI context to help you understand what this weight means for your health according to NHS guidance.
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.
How to Convert 6 Stone 5 to Kilograms
The conversion formula: To convert stone and pounds to kilograms, multiply the stone value by 6.35029, then add the pounds converted to kilograms (pounds × 0.453592).
- 6 stone = 38.1 kg
- 5 pounds = 2.3 kg
- Total: 40.4 kg
This calculation is precise and used by NHS health professionals, fitness trackers, and online health calculators across the UK. Use our free weight converter on this page to switch between kg, stone, and pounds instantly without a UK pharmacy calculation. The converter also helps if you need to check conversions for other weight values quickly.
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.
6 Stone 5 kg and Your BMI — What It Means
Whether 40.4 kg is a healthy weight depends entirely on your height. According to NHS guidance, a healthy weight falls within a BMI range of 18.5 to 24.9 for most adults. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a lower threshold of 18.5 to 22.9. Calculate your personal BMI using our free BMI calculator above — enter your height and weight to see where you fall on the health spectrum and understand what this means for your wellbeing.
- 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.
Is 40.4 kg a healthy weight?
That depends on your height. 40.4 kg could be a healthy weight for someone around 5ft 2in (158cm), but underweight for taller individuals or overweight for shorter ones. Use our free BMI calculator to check your personal BMI based on your actual height. Your GP can also advise you on what a healthy weight range is for you.
How do I convert stone to kilograms manually?
Multiply the stone value by 6.35029. For example: 6 stone × 6.35029 = 38.1 kg. Then add any additional pounds using the formula: pounds × 0.453592. For 5 pounds: 5 × 0.453592 = 2.3 kg. Total: 38.1 + 2.3 = 40.4 kg.
Why do UK doctors use kilograms instead of stone?
NHS healthcare professionals use kilograms because it's the standard metric unit used internationally and in medical research. However, many UK adults prefer stone for personal weight tracking. Our weight converter helps you switch between both units easily.
Can I use this conversion for health apps or fitness trackers?
Yes, absolutely. 6 stone 5 pounds equals 40.4 kg, which you can enter into any health, fitness, or medical app. If you're using a weight loss calculator or tracking your progress, accurate conversion between units is important for reliable results.
What's the difference between kilograms and stone?
Stone is a UK imperial unit; kilograms are metric. 1 stone = exactly 14 pounds. 1 kilogram = 2.20462 pounds. The metric system (kg) is used by scientists, doctors, and most countries worldwide, while stone remains popular in UK everyday usage.
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.