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 BMI Does 7.8 Pounds Give You?
7.8 pounds converts to approximately 3.54 kg. This is a very light weight on its own—too small to give a meaningful BMI reading for an adult. However, when combined with your total body weight, it represents part of your overall weight profile. To understand how your total weight affects your health, use our free BMI calculator above, which instantly shows your personal BMI range and how it compares to NHS weight categories. Whether you're tracking weight loss progress or simply curious about weight in kilograms, knowing how to convert pounds to kg helps you navigate UK health measurements.
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 3.54kg Fits Into Your Total Weight and BMI
7.8 pounds (3.54 kg) is a small amount of weight on its own—roughly equivalent to a large bag of sugar or a small bag of potatoes. In the context of weight loss or health tracking, this represents a modest loss or gain. To calculate your actual BMI, your total body weight combined with your height is what matters. The standard kilogram to stone conversion uses the ratio of 1 stone = 6.35 kg, making it easy to switch between metric and imperial weight measurements.
- 3.54 kg represents roughly 0.56 stone or 7.8 pounds
- A realistic weekly weight loss is 0.5–1 kg (1–2 lbs)
- BMI is calculated as weight (kg) ÷ height (m)²
- Your height is the key factor that determines your BMI at any given weight
Use our weight converter to instantly switch between kg, stone, and pounds whenever you need to. This helps you track your progress in whatever units feel most natural to you.
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.
Understanding BMI Categories and Their Meaning
The NHS uses standardised BMI categories to assess health risk. A BMI between 18.5 and 24.9 is considered a healthy weight for most adults; 25–29.9 is overweight; 30–34.9 is obese (Class I); and 35+ is severely obese. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the metric to imperial weight thresholds are lower due to higher health risks at the same BMI. BMI has important limitations—it doesn't distinguish between muscle and fat, so athletes may have a high BMI despite low body fat. Waist circumference and overall health context matter too.
Your GP can help interpret your personal BMI and advise whether weight management is right for you.
- 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 7.8 pounds to kg exactly?
Multiply 7.8 by 0.453592 to get 3.54 kg. You can also use our free weight converter tool on this page to convert instantly between pounds, kilograms, and stone. It's useful when tracking weight loss progress in different measurement units.
Will losing 7.8 pounds affect my BMI significantly?
Losing 3.54 kg (7.8 pounds) will affect your BMI based on your height. The change in BMI depends on your total weight and height. Use our free BMI calculator to see your starting BMI and calculate what your new BMI would be after losing this amount. Even modest weight loss can have health benefits.
What's the difference between stone and kg in UK health measurements?
The UK uses both. NHS clinical measurements use kilograms, but most people talk about their weight in stone and pounds. One stone equals 6.35 kg exactly. To convert kilograms to stone, divide by 6.35. Our weight converter makes switching between units fast and accurate.
Is 7.8 pounds a realistic weekly weight loss?
The NHS recommends losing 0.5–1 kg (1–2 lbs) per week for sustainable results. At 3.54 kg, this represents a loss of about 3–7 weeks at a healthy rate. Faster weight loss is possible with structured support, but slower, steady progress is usually more sustainable and preserves muscle mass.
How do I know if my weight is healthy for my height?
Calculate your BMI using your height and total weight. The NHS BMI calculator shows whether you're in the healthy range (18.5–24.9), overweight (25–29.9), or obese (30+). Our free BMI calculator on this page does this instantly and shows which NHS category you fall into based on your measurements.
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.