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 55kg in Stone and What's Your BMI?
55kg is equivalent to 8 stone 8.8 pounds in UK measurements. However, your BMI (a key health indicator) depends entirely on your height — the same weight can fall anywhere from a healthy range to overweight depending on how tall you are. This guide shows you what BMI 55kg gives you at different heights, plus where you stand according to NHS guidelines. Use our free BMI calculator above to find your exact BMI instantly, or continue reading for height-based examples and context.
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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.
55kg BMI at Different Heights
Here's what a weight of 55kg means for your BMI at various heights, using the standard BMI formula:
- At 160cm (5ft 3in): BMI = 21.5 (healthy weight, NHS category)
- At 165cm (5ft 5in): BMI = 20.2 (healthy weight)
- At 170cm (5ft 7in): BMI = 19.0 (healthy weight)
- At 175cm (5ft 9in): BMI = 17.9 (healthy weight, approaching lower limit)
- At 180cm (5ft 11in): BMI = 16.9 (underweight, NHS category)
At most adult heights, 55kg falls comfortably within the healthy weight range. The weight to stone conversion is straightforward (divide kilograms by 6.35029 to convert kilograms to stone), but BMI interpretation requires knowing your height. Try our weight converter above to switch between kg, stone, and pounds instantly.
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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 Limitations
The NHS defines a healthy BMI as 18.5 to 24.9 for most UK adults. At 55kg, you're likely in this range unless you're very tall. However, BMI has important limitations: it doesn't distinguish between muscle and fat, so an athletic person with high muscle mass may have a high BMI despite low body fat. BMI also doesn't account for where fat is stored — waist circumference matters too. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds (18.5 to 22.9 for healthy weight), reflecting higher health risks at the same weight. Your GP can provide personalised health guidance based on your complete health picture, not BMI alone.
- 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 55kg in stone and pounds?
55kg converts to 8 stone 8.8 pounds (sometimes rounded to 8st 9lbs). To convert any kilogram amount to stone, divide by 6.35029. This is the standard UK weight measurement used on bathroom scales and in everyday conversation.
Is 55kg a healthy weight?
Whether 55kg is healthy depends on your height. At most adult heights (160–175cm), 55kg gives a BMI in the healthy range (18.5–24.9 according to NHS guidelines). For someone 180cm or taller, it may be underweight. Use our free BMI calculator to check your personal BMI.
What BMI does 55kg give at 170cm?
At 170cm (5ft 7in), 55kg gives a BMI of 19.0, which falls squarely in the healthy weight range according to NHS guidelines (18.5–24.9). This is a common height in the UK, and 55kg represents a healthy weight for this height.
How do I calculate BMI from kg to stone?
First, convert kg to stone using the weight to stone converter (55kg ÷ 6.35 = 8.66 stone). Then use the BMI formula: weight (kg) ÷ height (m)². Easier: use our free BMI calculator above to do both at once.
Does BMI matter if I feel healthy?
BMI is a screening tool, not a complete health picture. It doesn't show muscle versus fat or account for fitness level. However, for most people, BMI correlates with health risk. If you're concerned about your weight or health, your GP can assess your individual situation and offer personalised guidance beyond just 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.