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 109kg in Stone and Pounds?
109kg converts to 17 stone 2.6 pounds in UK measurements. However, what this weight means for your health depends entirely on your height. The same weight gives a very different BMI for someone who is 5ft 4in compared to someone who is 6ft 2in. Use our free BMI calculator above to find your personal BMI instantly by entering your height, or scroll down to see example BMI values at common heights to understand where you sit on the NHS health scale.
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.
109kg BMI at Different Heights
At 109kg, your BMI changes significantly depending on your height. Here are example BMI values at common UK heights:
- 160cm (5ft 3in): BMI of 42.6 — Severely obese (Class III)
- 165cm (5ft 5in): BMI of 40.0 — Severely obese (Class III)
- 170cm (5ft 7in): BMI of 37.7 — Obese (Class II)
- 175cm (5ft 9in): BMI of 35.5 — Obese (Class II)
- 180cm (5ft 11in): BMI of 33.6 — Obese (Class I)
- 185cm (6ft 1in): BMI of 31.8 — Obese (Class I)
To calculate your exact BMI using the standard formula, divide 109 by your height in metres squared. The free BMI calculator on this page gives gradual improvement — simply enter your height to see your personal BMI category.
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 Your BMI Category
According to NHS guidelines, a healthy BMI is between 18.5 and 24.9. At 109kg, most adults would fall into the obese categories unless they are quite tall. It's important to note that BMI has limitations — it doesn't distinguish between muscle and fat, so athletes or very muscular individuals may have a higher BMI despite low body fat.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds due to higher health risks at the same weight. If you're concerned about your health, your GP can provide personalised advice and discuss weight management options tailored to your individual circumstances.
- 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 formula for converting kg to stone?
Divide kilograms by 6.35029. So 109kg ÷ 6.35029 = 17.17 stone, which is 17 stone and 2.6 pounds. Use our free weight converter above to switch between kg, stone, and pounds instantly without a UK pharmacy calculation.
Does 109kg mean I'm overweight?
It depends on your height. At 109kg, most adults fall into the obese BMI category, though some taller individuals may be in the overweight range. Your GP can assess your individual health and discuss whether weight management might be beneficial for you.
What's a healthy weight for someone 5ft 7in tall?
For someone 170cm (5ft 7in), a healthy BMI weight range is approximately 53–72kg. At 109kg, this would be above the healthy range. Try our free BMI calculator above to explore healthy weight ranges for your specific height.
Can I lose weight safely with prescription medication?
Prescription weight loss medications like Mounjaro and Wegovy are available in the UK for eligible adults. These work best alongside lifestyle changes. You'll need a clinical assessment from a GP or prescriber to determine if medication is appropriate for you.
What does "severely obese" mean on the BMI scale?
Severely obese (Class III) refers to a BMI of 40 or above. This category indicates increased health risks including type 2 diabetes, heart disease, and sleep apnoea. Your GP can discuss health management options and support available to you.
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.