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
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2 Stone 9 in Kg — Quick Conversion Guide
2 stone 9 pounds (2st 9lbs) converts to exactly 16.78 kilograms. This straightforward conversion helps you switch between UK imperial measurements and metric units, which is useful when using NHS health guidance or international health information. Whether you're checking your weight against health thresholds or using a uk health guide, understanding how to convert between stone and kilograms makes it easier to compare your weight across different measurement systems. Our free weight converter above lets you switch between any weight units instantly.
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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 to Convert 2 Stone 9 to Kilograms
To convert 2 stone 9 pounds to kg, use the standard conversion formula. One stone equals exactly 6.35029 kilograms, and one pound equals 0.453592 kg. Breaking this down:
- 2 stone = 2 × 6.35029 = 12.70058 kg
- 9 pounds = 9 × 0.453592 = 4.082328 kg
- Total = 12.70058 + 4.082328 = 16.78 kg
This conversion is precise and used across NHS guidance, health calculators, and international health records. The same metric applies whether you're tracking weight for health monitoring, medication dosing, or fitness purposes. Use our weight converter tool on this page to convert between stone, pounds, and kilograms instantly for any weight.
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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.
What Does 16.78 kg Mean for Your Health?
At 16.78 kg, this weight is typically relevant for infants or young children rather than adults. For UK health information purposes, NHS guidance uses BMI (body mass index) to assess whether an adult weight is healthy. BMI takes both weight and height into account, which is why weight alone doesn't determine health status.
If you're checking a child's weight, always consult your GP or health visitor — children use age and sex-specific growth charts, not adult BMI categories. For adult weight management and nhs health advice, use our free BMI calculator above to see where your weight sits against healthy thresholds for your height. Track your progress over time using our free progress tracker.
- 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 the exact conversion from 2 stone 9 to kg?
2 stone 9 pounds (2st 9lbs) converts to exactly 16.78 kilograms. To calculate: multiply stone by 6.35029 and pounds by 0.453592, then add them together. This conversion is used by the NHS and all UK health services.
Is 16.78 kg a healthy weight?
At 16.78 kg, this weight is too low for a healthy adult and is typically associated with infants or small children. UK health guidance uses BMI (body mass index) to assess adult weight health, which requires both weight and height. Consult your GP for personalised advice about healthy weight for your age and height.
How do I convert stone and pounds to kg quickly?
Use our free weight converter tool on this page to instantly switch between any weight units. Alternatively, multiply stone by 6.35 and pounds by 0.45, then add them together. This simple method gives you an approximate kg figure without a calculator.
Why do UK adults use stone and pounds instead of kilograms?
The UK traditionally uses imperial measurements for everyday weight, though the NHS also records weight in kilograms for clinical purposes. Both systems are in common use. Understanding both measurements helps you work with health professionals and access international health resources easily.
Can I use this conversion for medication dosing?
Weight conversions like this are sometimes used in healthcare contexts, but medication dosing should always be confirmed by your prescriber or pharmacist. Never adjust medication doses based on weight conversion alone — always consult your GP or healthcare professional for personalised guidance.
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.