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 7.8 Kg In Stone and What Does It Mean for Your BMI?
7.8 kg converts to approximately 1 stone and 3 pounds. However, your BMI — and what this weight means for your health — depends entirely on your height. A person who weighs 7.8 kg is typically a young child, as this is an unusually low weight for an adult. If you're looking to understand weight in the context of adult health, use our free weight converter above to switch between kg, stone, and lbs, then use our BMI calculator to find your personal health category according to NHS guidelines.
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.
How 7.8 Kg Converts to Stone and What Your BMI Would Be
To convert 7.8 kg to stone, divide by 6.35: 7.8 kg ÷ 6.35 = 1.23 stone, which is approximately 1 stone 3 pounds.
Your BMI at 7.8 kg depends on height. Here are example BMI values across different adult heights:
- 160 cm (5ft 3in): BMI = 30.5 (Obese Class I) — significantly above healthy range
- 170 cm (5ft 7in): BMI = 27.1 (Overweight) — above NHS healthy range
- 180 cm (5ft 11in): BMI = 24.1 (Healthy weight) — within NHS healthy range of 18.5–24.9
- 190 cm (6ft 3in): BMI = 21.6 (Healthy weight) — comfortably within healthy range
Use our BMI calculator on this page to find your exact BMI and NHS category based on your own 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.
Understanding BMI Categories and When 7.8 Kg Is Healthy
According to NHS guidelines, a healthy BMI is between 18.5 and 24.9. At 7.8 kg, whether your weight is healthy depends entirely on your height — as shown above, the same weight can be healthy for a taller person but overweight or obese for someone shorter.
Important to note: BMI has limitations. It does not account for muscle mass, bone density, or where fat is stored on your body. Your GP can provide personalised health advice beyond BMI alone. If you're concerned about your weight and health, your GP is the best resource for individualised guidance about what a healthy weight means for you specifically.
- 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.
Is 7.8 kg a healthy weight?
For adults, 7.8 kg is extremely low and would indicate significant underweight or a serious health issue. Whether any weight is healthy depends on height, age, and individual health factors. A GP can assess your personal situation and offer appropriate guidance.
How do I convert 7.8 kg to stone quickly?
Divide 7.8 by 6.35. This gives 1.23 stone, or approximately 1 stone 3 pounds. Our free weight converter above lets you convert between kg, stone, and lbs instantly for any weight.
What BMI does 7.8 kg give at different heights?
At 160 cm, BMI is 30.5 (obese). At 170 cm, BMI is 27.1 (overweight). At 180 cm, BMI is 24.1 (healthy). At 190 cm, BMI is 21.6 (healthy). Use our BMI calculator to find your exact BMI for your height.
What are the NHS BMI categories?
According to NHS guidelines: underweight below 18.5, healthy weight 18.5–24.9, overweight 25–29.9, obese 30–34.9, severely obese 40+. South Asian, Black African, and Chinese adults have lower recommended thresholds due to higher cardiovascular risk.
Does BMI alone tell me if I'm at a healthy weight?
No. BMI is a useful screening tool but has important limitations — it doesn't distinguish muscle from fat, account for waist circumference, or consider age or genetics. Your GP can provide a fuller picture of your health beyond BMI.
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.