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 42kg in Stone?
42kg converts to 6 stone and 8.2 pounds — a weight that applies to many UK adults, including some younger people and those managing specific health conditions. Using our free weight converter, you can instantly switch between metric and imperial measurements. Whether you're tracking your health using NHS guidance, monitoring weight loss progress, or simply need to understand what 42kg means in UK measurements, this guide covers the key information and health context for this weight.
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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.
How to Convert 42kg to Stone and Pounds
Converting 42kg to stone uses a simple formula. One stone equals exactly 6.35029kg, and one pound equals 0.453592kg. To convert 42kg to stone and pounds: divide 42 by 6.35029 to get stones (6.62 stone), then multiply the decimal (0.62) by 14 to get the remaining pounds (8.7lbs). This gives you 6 stone 8.2 pounds.
Alternatively, you can multiply 42kg by 2.20462 to convert directly to pounds: 42kg = 92.6 pounds. Use our free weight converter on this page to switch between kg, stone, and pounds instantly — no calculation needed.
Understanding your weight in both metric and imperial measurements is useful for NHS health appointments, monitoring progress with our free progress tracker, and comparing your weight against UK health guidelines.
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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 42kg a Healthy Weight?
Whether 42kg is a healthy weight depends on your height and age. According to NHS guidelines, a healthy BMI for adults is between 18.5 and 24.9. At 42kg, someone who is 148cm (4ft 10in) tall would have a BMI of 19.1 — within the healthy range. However, the same weight at a taller height (e.g. 170cm) would result in a BMI of 14.5 — underweight.
Use our free BMI calculator above to find your personal BMI instantly based on your exact height and weight. For South Asian, Chinese, Black African, or Black Caribbean adults, the NHS recommends slightly lower BMI thresholds for better health outcomes. If you're concerned about whether 42kg is right for you, your GP can provide personalised health advice.
- 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 42kg in stone and pounds?
42kg equals 6 stone 8.2 pounds (or 92.6 pounds). To convert, divide 42kg by 6.35029 to get stone, or multiply by 2.20462 to get pounds. Our free weight converter above will do this instantly for any weight you enter.
Is 42kg underweight for an adult?
It depends on your height. At 148cm (4ft 10in), 42kg gives a BMI of 19.1 (healthy). At 170cm (5ft 7in), it gives a BMI of 14.5 (underweight). Use our BMI calculator to check your personal BMI — your GP can advise if your weight is right for your health.
How much weight would I lose on Wegovy at 42kg starting weight?
Clinical trials (STEP-1) showed that people on Wegovy 2.4mg lost approximately 14.9% of their body weight on average. At 42kg, this could represent around 6.3kg loss, though individual results vary significantly. Our GLP-1 weight loss calculator can show projected outcomes based on your starting weight and dose.
Is 42kg a low weight for the UK?
42kg is lighter than the average UK adult (men average 85.7kg, women 71.6kg) but not unusually low if you're a young adult or shorter in height. NHS guidance focuses on BMI rather than absolute weight — context matters more than the number itself.
Can I track weight changes from 42kg?
Yes. Our free progress tracker lets you log your weight regularly and see trends over time, whether you're aiming to maintain, gain, or lose weight. Tracking helps you stay motivated and spot patterns in your health journey.
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.