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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What is 42kg in Stone and Pounds? BMI Guide for UK Adults
42 kilograms equals 6 stone and 8 pounds (or 92.6 lbs) in UK measurements. Whether this weight is healthy depends entirely on your height — the same weight gives very different BMI results at different heights. Use our free BMI calculator above to find your personal BMI instantly. This guide shows you what 42kg means for your health at common UK heights, and explains the NHS BMI categories that help determine whether your weight falls in a healthy range.
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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.
What BMI Does 42kg Give at Different Heights?
At 42kg, your BMI varies significantly depending on your height. Here are typical BMI values at common heights:
- At 150cm (4ft 11in): BMI 18.7 — healthy weight range
- At 155cm (5ft 1in): BMI 17.5 — healthy weight range
- At 160cm (5ft 3in): BMI 16.4 — underweight
- At 165cm (5ft 5in): BMI 15.4 — underweight
- At 170cm (5ft 7in): BMI 14.5 — underweight
- At 175cm (5ft 9in): BMI 13.7 — underweight
These calculations use the standard BMI formula: weight (kg) ÷ height (m)². Use the weight converter on this page to switch between kg, stone, and lbs whenever you need precise conversions.
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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.
Understanding BMI Categories and Healthy Weight Ranges
The NHS BMI categories apply to all UK adults:
- Below 18.5 = underweight
- 18.5 to 24.9 = healthy weight
- 25.0 to 29.9 = overweight
- 30.0+ = obese
Important: BMI has limitations. It doesn't account for muscle mass, so athletes may have a high BMI with low body fat. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds. If you're concerned about your weight, your GP can provide personalised advice based on your individual health, family history, and any existing conditions.
- 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 42kg to stone and pounds exactly?
42kg equals 6 stone and 8 pounds (6st 8lbs). To calculate: divide 42 by 6.35029 to get stone, then multiply the decimal by 14 to get remaining pounds. Alternatively, use our free weight converter above — it calculates instantly and shows all units at once.
Is 42kg a healthy weight?
That depends on your height. At 42kg, you'll have a healthy BMI only if you're around 150–153cm tall. At taller heights, this weight may fall into the underweight category. Use our free BMI calculator to check your personal result based on your exact height.
What is the healthy weight range at my height if I weigh 42kg?
The healthy BMI range (18.5–24.9) gives different weight ranges at each height. For example, at 160cm the healthy range is 47–63kg; at 170cm it's 53–72kg. Calculate your personal healthy weight range using our BMI calculator above.
Does 42kg make sense for an adult?
42kg is relatively light for most UK adults. The average UK adult woman weighs about 71.6kg, and the average man weighs about 85.7kg. At 42kg, you'd likely fall into the underweight category unless you're quite short (under 5ft tall). Discuss with your GP if you have concerns.
How does 42kg compare to stone measurements I see in the UK?
42kg is 6 stone 8 pounds — below the average UK adult weight. In UK stone-based measurements, one stone equals 6.35kg. So 42kg is slightly over 6 stone. The weight converter on this page shows all conversions between kg, stone, and pounds instantly.
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.