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's Your BMI at 8.3 Kg?
8.3 kg converts to 1 stone 4.5 lbs in UK measurements. However, your BMI (body mass index) depends on your height, not just your weight. Use our free BMI calculator above to find your exact BMI, or read on to see how 8.3 kg compares across different heights and where it falls within NHS health categories. Understanding your BMI helps you assess whether your weight is in a healthy range for your individual height.
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.
BMI at 8.3 Kg — Examples at Different Heights
At 8.3 kg, your BMI varies significantly depending on your height. Here are typical examples using the BMI formula: weight (kg) ÷ height (m)².
- At 5ft 0in (152cm): BMI = 36.0 — falls into Obese (Class I) category
- At 5ft 3in (160cm): BMI = 32.4 — falls into Obese (Class I) category
- At 5ft 6in (168cm): BMI = 29.4 — falls into Overweight category
- At 5ft 9in (175cm): BMI = 27.0 — falls into Overweight category
- At 6ft 0in (183cm): BMI = 24.8 — falls into Healthy weight category
Use our weight converter to switch between kg, stone, and pounds. At 8.3 kg you're likely a child or very lightweight adult — if calculating for an adult, check your figures as typical adult weight is much higher.
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 BMI Categories and What They Mean
The NHS uses standardised BMI ranges to assess weight status for adults:
- Below 18.5: Underweight
- 18.5–24.9: Healthy weight
- 25.0–29.9: Overweight
- 30.0–34.9: Obese (Class I)
- 35.0–39.9: Obese (Class II)
- 40.0+: Severely obese (Class III)
Important: BMI is a screening tool only and doesn't account for muscle mass, bone density, or where fat is stored. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds. Always consult your GP for personalised health guidance.
- 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 8.3 kg to stone and pounds?
To convert kilograms to stone, divide by 6.35029. So 8.3 kg ÷ 6.35029 = 1.307 stone, which equals 1 stone 4.5 lbs. You can use our free weight converter above to switch instantly between kg, stone, and pounds for any weight.
What BMI should I aim for according to NHS guidelines?
The NHS recommends a healthy BMI between 18.5 and 24.9 for most adults. If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS suggests a target of 18.5 to 22.9. Use our free BMI calculator to check your personal BMI and see which category you fall into.
Is 8.3 kg a normal weight for an adult?
8.3 kg is extremely low for an adult — it's typical only for infants or very young children. If you're calculating an adult weight, please check your figures. For children, use the NHS Healthy Weight Calculator rather than standard BMI categories, as children's BMI uses age and sex-specific growth charts.
Why does BMI depend on height?
BMI accounts for how weight is distributed across your height. Two people weighing the same but with different heights will have very different BMIs. Taller individuals can carry more weight in a healthy range, which is why height is essential to calculating whether your weight is appropriate for your body.
Can BMI be inaccurate?
Yes — BMI doesn't distinguish between muscle and fat, so athletes may have a high BMI despite low body fat. BMI also doesn't account for age, sex, or ethnicity properly without adjustment. For a complete health picture, your GP may also measure waist circumference and consider your overall health, not just BMI alone.
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.