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 8.4 kg in Stone and What Does It Mean for Your BMI?
8.4 kg is equal to 1 stone and 3.2 pounds in UK measurements. However, your BMI depends entirely on your height — the same weight can give very different BMI results for different people. Below, we've calculated what 8.4 kg means for BMI across a range of typical adult heights, and shown you which NHS health category each falls into. Use our free BMI calculator above to check your personal BMI instantly and get tailored health context.
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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.
BMI for 8.4 kg at Different Heights
To convert 8.4 kg to stone and understand your BMI, you need to know your height. Here's what 8.4 kg gives you at common heights:
- 5ft (152 cm): BMI = 36.4 — Obese (Class I) category
- 5ft 4in (163 cm): BMI = 31.4 — Obese (Class I) category
- 5ft 8in (173 cm): BMI = 28.1 — Overweight category
- 5ft 10in (178 cm): BMI = 26.6 — Overweight category
- 6ft (183 cm): BMI = 25.1 — Healthy weight category
- 6ft 2in (188 cm): BMI = 23.7 — Healthy weight category
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds — so your health category may differ slightly even at the same weight and height.
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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.
NHS BMI Categories and Why BMI Has Limits
According to NHS guidelines, healthy BMI ranges from 18.5 to 24.9 for most adults. Overweight is 25.0–29.9, and obesity begins at 30 and above. However, BMI is a screening tool only — it doesn't account for muscle mass, where fat is stored, age, or overall fitness level. An athlete might have a high BMI but low body fat. Conversely, someone with a healthy BMI could have high body fat. Use our weight converter to check your measurements in different units, and talk to your GP about what your BMI means for your individual health, especially if you have other health conditions or concerns.
- 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 8.4 kg to stone manually?
Divide 8.4 by 6.35029 to get stone (1.32 stone), then multiply the decimal by 14 to get pounds (4.48 lbs, often rounded to 1 stone 3–4 lbs). Our weight converter above does this instantly for you.
Is 8.4 kg a healthy weight for an adult?
For an adult, 8.4 kg is extremely low and would indicate severe malnutrition. An adult healthy weight typically ranges from 50–100+ kg depending on height. If you're concerned about underweight, please see your GP.
What does my BMI tell me about my health?
BMI is a useful first screening tool but has limitations. It indicates whether your weight falls in a healthy range for your height, but doesn't account for muscle, bone density, or fat distribution. Your GP can assess your individual health risk factors.
Do different ethnic groups have different healthy BMI ranges?
Yes. The NHS recommends lower BMI thresholds for adults of South Asian, Chinese, Black African, and Black Caribbean heritage due to higher health risk at lower BMI levels. Check with your GP for personalised guidance.
How can I track my weight and BMI over time?
Use our free progress tracker to log your weight, calculate your BMI at each check-in, and monitor trends. Regular tracking helps identify patterns and supports sustainable health changes.
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.