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 40 kg in stone and pounds?
40 kilograms is equal to 6 stone and 4.7 pounds (or approximately 6st 5lbs in practical terms). This conversion uses the standard kilogram to stone conversion formula, which divides kilograms by 6.35029. Whether you're checking a weight measurement, tracking progress, or understanding NHS health guidance, our free weight converter above can instantly switch between kg, stone, and pounds. This weight is considered underweight to healthy depending on height — we'll cover BMI context below.
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.
40 kg to stone conversion formula and nearby values
To convert 40 kg to stone, divide by 6.35029. So 40 ÷ 6.35029 = 6.3 stone, or 6 stone 4.7 pounds.
The conversion formula works both ways: to convert stone to kilograms, multiply by 6.35029. Below is a reference table showing 40kg alongside nearby weights in both metric and imperial — useful if you're checking conversions for different values:
- 35 kg = 5st 6.4lbs
- 37 kg = 5st 12.3lbs
- 39 kg = 6st 2lbs
- 40 kg = 6st 4.7lbs
- 41 kg = 6st 7.4lbs
- 43 kg = 6st 11.2lbs
- 45 kg = 7st 1lbs
Clinically BackedWeight Loss
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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.
Is 40 kg a healthy weight? BMI context for UK adults
Whether 40 kg is healthy depends entirely on height. A person 163 cm (5ft 4in) tall weighing 40 kg would have a BMI of 15, which is in the healthy range (18.5–24.9). Someone 150 cm (4ft 11in) tall at 40 kg would have a BMI of 17.8, also healthy. However, someone 190 cm (6ft 3in) tall at 40 kg would be significantly underweight. Calculate your personal BMI using our free BMI calculator above to understand whether this weight is appropriate for your specific height. For NHS guidance, healthy weight falls within a BMI of 18.5–24.9 for most adults — though thresholds are lower for South Asian and Black African heritage populations.
- 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 40 kg to pounds only?
Multiply 40 kg by 2.20462. So 40 × 2.20462 = 88.18 pounds (approximately 88 lbs). This is useful if you need a pure pounds figure rather than stone and pounds combined.
Is 40 kg considered underweight?
It depends on height. At average UK adult heights (163–175 cm), 40 kg would be underweight. However, 40 kg is a healthy weight for children and shorter adults. Use our BMI calculator to check if this weight is healthy for your specific height and age.
How does 40 kg compare to average UK body weights?
Average UK adult weights are approximately 85.7 kg for men and 71.6 kg for women — so 40 kg is significantly below average adult weight. This weight is typical for children aged 10–12, or shorter/lighter adults.
What's the difference between stone and pounds?
One stone equals exactly 14 pounds. So 6 stone = 84 pounds, plus the extra 4.7 pounds = 88.7 pounds total. UK adults traditionally use stone and pounds for body weight, whilst the NHS uses kilograms for medical records.
Can I track 40 kg weight changes with MyWeightCheck?
Yes. Use our free progress tracker on this page to log your weight in kilograms and track changes over time. It displays your progress in both kg and stone, helping you monitor your journey alongside BMI and healthy weight context.
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.