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 Kg In Stone And Pounds?
8 kilograms equals 1 stone and 3.3 pounds (or approximately 1st 3lbs in UK measurements). This is a very light weight for an adult — typically the weight of an infant or small child. To understand what this weight means for health, you need to consider height, as BMI depends on both weight and height together. Use our free BMI calculator above to find your personal BMI, or see the example BMI values below for different heights at this weight.
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.
8 Kg BMI At Different Heights
BMI (Body Mass Index) combines weight and height to give a health screening value. At 8 kg, here's what BMI would be at various adult heights using the standard kilogram to stone conversion:
- At 150 cm (4ft 11in): BMI of 35.6 — Obese Class I (NHS category)
- At 160 cm (5ft 3in): BMI of 31.3 — Obese Class I
- At 170 cm (5ft 7in): BMI of 27.7 — Overweight (NHS category)
- At 180 cm (5ft 11in): BMI of 24.7 — Healthy weight (NHS category)
- At 190 cm (6ft 3in): BMI of 22.2 — Healthy weight
This illustration shows why height matters enormously. At 8 kg, only taller adults would fall into the healthy weight range. For your own accurate BMI, use the weight converter and BMI calculator on this page to enter your exact height.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 Weight Categories And BMI Limitations
The NHS defines healthy BMI as 18.5 to 24.9 for most UK adults. At 8 kg, very few adults would achieve this range — it's an exceptionally low weight. Important to note: BMI does not distinguish between muscle and fat, so it's just one screening tool. Your GP may also assess waist circumference, fitness level, and overall health rather than BMI alone.
For adults of South Asian, Chinese, Black African, or Black Caribbean backgrounds, the NHS recommends lower BMI thresholds (healthy range 18.5–22.9), reflecting higher health risks at the same BMI level. If you're concerned about your weight or BMI, your GP can provide personalised guidance based on your complete health picture.
- 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 kilograms to stone accurately?
Divide kilograms by 6.35029 to get stone. So 8 kg ÷ 6.35 = 1.26 stone, which is 1 stone and 3.3 pounds. You can also use our free weight converter above to switch between kg, stone, and pounds instantly.
Is 8 kg a healthy weight for an adult?
8 kg is extremely low for any adult. It's typically the weight of an infant or toddler. If you weigh 8 kg, your GP should assess your health urgently. If you meant a different weight, use the weight converter on this page to find your accurate stone and pounds conversion.
What does BMI mean and why is height important?
BMI (Body Mass Index) is calculated as weight ÷ height². That's why two people at 8 kg can have very different BMI values depending on their height. A taller person would have a lower BMI than a shorter person at the same weight. Use our BMI calculator to find your personal BMI instantly.
What are the NHS BMI categories?
The NHS BMI categories are: Underweight (below 18.5), Healthy weight (18.5–24.9), Overweight (25–29.9), Obese Class I (30–34.9), Obese Class II (35–39.9), and Severely Obese (40+). For South Asian and Black African backgrounds, thresholds are lower — healthy weight is 18.5–22.9.
Should I be concerned if my BMI falls outside the healthy range?
If your BMI is outside the healthy range, it's worth discussing with your GP. They can assess your individual health, medical history, fitness level, and family history rather than relying on BMI alone. Use the BMI calculator on this page to check your BMI, then book a GP appointment to discuss your health in 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.