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
8.4 Kg to Pounds — What BMI Does This Weight Give?
8.4 kilograms is equal to approximately 18.5 pounds. However, your BMI at this weight depends entirely on your height — the same weight can fall into different NHS health categories depending on how tall you are. Using our free BMI calculator, you can instantly check your personal BMI by entering your height and weight. This guide shows you what BMI this weight gives at various heights, and where you fall on the NHS health scale.
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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.
8.4 Kg to Pounds at Different Heights
At 8.4 kg (18.5 lbs), your BMI varies significantly based on height. Here's what your BMI would be at different heights using the standard kilogram to stone conversion and BMI formula:
- 150 cm (4ft 11in): BMI 37.4 (Obese Class I)
- 160 cm (5ft 3in): BMI 32.8 (Obese Class I)
- 170 cm (5ft 7in): BMI 27.5 (Overweight)
- 175 cm (5ft 9in): BMI 27.4 (Overweight)
- 180 cm (5ft 11in): BMI 25.9 (Overweight)
- 190 cm (6ft 3in): BMI 23.2 (Healthy weight)
Remember, this is a very low body weight — 8.4 kg would typically only apply to infants or very young children, not adults. For adult BMI assessment, use our free weight converter and BMI calculator above to check your personal measurements.
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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 NHS BMI Categories and Their Limits
The NHS classifies adult BMI into five main categories: underweight (below 18.5), healthy weight (18.5–24.9), overweight (25.0–29.9), obese (30.0–39.9), and severely obese (40.0 and above). However, BMI has important limitations — it doesn't distinguish between muscle and fat, doesn't account for where fat is stored, and may be less accurate for athletes, elderly people, or those with high muscle mass. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds due to higher health risks at lower weights. Waist circumference is equally important for assessing health risk.
- 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 8.4 kg in pounds exactly?
8.4 kilograms equals 18.51 pounds (lbs). This is calculated by multiplying 8.4 by 2.20462, the standard conversion factor. If you need to convert to stone and pounds (the traditional UK measurement), 8.4 kg is approximately 1 stone 4.5 pounds. Use our free weight converter above to instantly convert between kg, stone, and pounds.
Is 8.4 kg a healthy weight for an adult?
No, 8.4 kg is extremely low and would not be a healthy weight for any adult. It's appropriate only for newborns or very young infants. For adults, healthy weight depends on height. Use our BMI calculator to check if your actual weight is in a healthy range for your height according to NHS guidelines.
Why does BMI matter if I know my weight in pounds?
BMI matters because weight alone doesn't indicate health — your height is crucial too. Someone weighing 18.5 pounds could have a very different BMI (and health risk) depending on whether they're 150 cm or 190 cm tall. BMI combines both measurements to give a meaningful health indicator. That's why converting to BMI using the BMI calculator is more useful than just knowing your weight in pounds.
What's the difference between stone and pounds for weight?
In UK measurements, 1 stone equals exactly 14 pounds. So weight in stone and pounds (e.g., "10 stone 8 pounds") combines both units. Kilograms are metric. The metric to imperial weight conversion formula is: 1 kg = 2.20462 lbs, or 1 kg = 0.157473 stone. Our weight converter handles all three systems instantly.
How do I check if my weight is healthy?
Calculate your BMI using your actual height and weight — use our free BMI calculator above. Find where your BMI falls in the NHS categories (healthy weight is 18.5–24.9 for most adults, but lower for South Asian and other heritage groups). You can also track progress over time with our free progress tracker. If you're concerned about your health at any weight, speak to your GP for personalised advice.
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.