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
15.5 Kg to Lbs — What's Your BMI?
15.5 kg equals 34.2 pounds (lbs). However, your BMI — a key health screening measure — depends entirely on your height. Use our free BMI calculator above to find your exact BMI, or read on to see how this weight falls across the NHS BMI categories at different heights. Understanding where you stand helps you make informed health decisions with your GP.
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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.
15.5 Kg BMI at Different Heights
At 15.5 kg, your BMI varies significantly depending on your height. Here's how this weight translates across common UK heights:
- 150 cm (4ft 11in): BMI 69.1 (Severely obese Class III)
- 160 cm (5ft 3in): BMI 60.5 (Severely obese Class III)
- 170 cm (5ft 7in): BMI 53.6 (Severely obese Class III)
- 175 cm (5ft 9in): BMI 50.6 (Severely obese Class III)
- 180 cm (5ft 11in): BMI 47.8 (Severely obese Class III)
- 190 cm (6ft 3in): BMI 42.8 (Severely obese Class III)
At 15.5 kg, regardless of height, all BMI values fall well into the severely obese range. To understand your personal BMI and health context, calculate your exact figure using the weight converter and BMI calculator on this page, then discuss your health with your GP.
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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 NHS BMI Categories
The NHS defines BMI categories to help assess health risk. A BMI of 40 or above is classified as severely obese (Class III), indicating significantly elevated health risks including type 2 diabetes, cardiovascular disease, and joint problems.
Important: BMI has limitations — it doesn't distinguish between muscle and fat, and doesn't account for where fat is stored. Your waist circumference matters too. For South Asian, Chinese, Black African, or Caribbean adults, lower BMI thresholds apply due to higher health risk at the same BMI. Always discuss your weight and health with your GP, who can assess your individual circumstances and recommend appropriate support.
- 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 15.5 kg in pounds?
15.5 kg equals 34.2 lbs (pounds). This is a straightforward metric to imperial conversion. Use the weight converter on this page to convert between kg, stone, and pounds instantly for any weight.
Is 15.5 kg a healthy weight for an adult?
No — 15.5 kg is significantly below a healthy weight for any adult. A healthy weight for adults typically ranges from approximately 50 kg upwards, depending on height. If you weigh 15.5 kg, please speak urgently with your GP about your health and nutrition.
What BMI does 15.5 kg give?
At 15.5 kg, your BMI depends on your height. For someone 170 cm tall, the BMI would be approximately 53.6 (severely obese Class III). Use our BMI calculator above to find your exact BMI by entering your height and weight.
What are the NHS BMI categories?
The NHS defines: underweight (below 18.5), healthy weight (18.5–24.9), overweight (25.0–29.9), obese Class I (30.0–34.9), obese Class II (35.0–39.9), and severely obese Class III (40.0+). Lower thresholds apply for South Asian and Black African/Caribbean adults due to higher health risk at the same BMI.
Should I be concerned about a BMI in the severely obese range?
Yes — a severely obese BMI (40+) is associated with significantly increased risk of serious health conditions. Speak with your GP as soon as possible. They can assess your individual health, discuss causes of weight, and recommend appropriate support which may include lifestyle changes, dietary advice, or in some cases, specialist weight management services.
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.