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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BMI Calculator Using kg and cm — UK Guide
Calculating your BMI using kilograms and centimetres is the metric method used by the NHS and most healthcare systems worldwide. BMI (body mass index) is a simple screening tool that estimates whether your weight is healthy for your height. To find your BMI, simply enter your weight in kg and height in cm into our free BMI calculator above — it instantly shows your result and tells you which NHS category you fall into. This guide explains how the calculation works, provides conversion context for UK measurements, and shows typical healthy weight ranges across different heights.
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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.
BMI Conversion Table — Weight and Height Ranges
Use this comprehensive table to understand how weight in kilograms and height in centimetres translate to BMI scores across typical adult ranges. The BMI formula is straightforward: divide weight (kg) by height in metres squared. For example, at 170cm tall, a weight of 70kg gives a BMI of 24.2, which falls in the healthy weight range according to NHS guidelines.
- 40–50kg at 160cm: BMI 15.6–19.5 (healthy to underweight)
- 60–70kg at 170cm: BMI 20.8–24.2 (healthy weight range)
- 75–85kg at 170cm: BMI 25.9–29.4 (overweight)
- 90–100kg at 170cm: BMI 31.1–34.6 (obese class I)
- 110–130kg at 170cm: BMI 38.1–45.1 (obese class II–III)
The healthy BMI UK range is 18.5 to 24.9 for most adults. Those of South Asian, Chinese, Black African, or Black Caribbean heritage should use lower thresholds: 18.5 to 22.9. Use our free weight converter to switch between kg, stone, and pounds instantly if you prefer imperial measurements.
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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.
When to Use kg and cm — NHS Clinical Context
In the UK, healthcare professionals use kilograms and centimetres for clinical measurements, while many adults still prefer stone and pounds in everyday life. The NHS BMI categories are all defined using metric measurements. When you visit your GP or attend hospital, your weight will be recorded in kg and your height in cm. This metric approach makes it easy to compare your results with clinical research and NHS guidance. To calculate your BMI accurately, ensure your measurements are precise — weigh yourself at the same time each day (ideally morning before eating) and measure your height without shoes. If you need to know what is a healthy BMI for your specific situation, including ethnicity-adjusted thresholds, your GP can provide personalised advice.
- 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 a healthy BMI in kg and cm measurements?
A healthy BMI is between 18.5 and 24.9 for most UK adults. For example, at 170cm (5ft 7in), this means weighing between approximately 53kg and 72kg. For South Asian, Chinese, Black African, or Black Caribbean adults, the healthy range is 18.5 to 22.9. Use our BMI calculator above to find your personal range.
How do I calculate BMI using kg and cm?
The BMI formula is: weight (kg) ÷ [height (cm) ÷ 100]². For example: 70kg ÷ (1.70)² = 24.2 BMI. Our free BMI calculator does this instantly — simply enter your weight in kg and height in cm above and it displays your result immediately.
What does overweight BMI mean in metric measurements?
An overweight BMI is between 25.0 and 29.9. For instance, at 170cm tall, this means weighing between approximately 73kg and 91kg. This range indicates increased health risk, though individual health depends on many factors. Your GP can advise if lifestyle changes or further assessment would be helpful.
Why does the NHS use kg and cm instead of stone and pounds?
The NHS uses metric measurements (kg and cm) because they align with international clinical standards, making it easy to compare health data globally and with research studies. However, many UK adults still use stone and pounds — our weight converter lets you switch between both systems easily.
Should I use an overweight BMI calculator or the standard one?
Use the same BMI calculator for everyone — there's no separate "overweight" version. Our free BMI calculator works for all adults and shows you which NHS category you fall into, whether healthy, overweight, or obese. Individual circumstances vary, so discuss results with your GP for personal 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.