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
Weight Calculator and Conversion Guide for UK Adults
Working out your weight in different measurements is essential for understanding your health status in the UK. Whether you need to convert kilograms to stone, calculate your BMI, or check if you're within a healthy weight range, having the right tools makes it straightforward. Our weight converter and BMI calculator help you instantly see your weight across all UK measurements and assess your health position against NHS guidelines. This guide explains how weight conversion works, why it matters for your health, and how to use these tools effectively.
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.
Why Weight Conversion and BMI Calculation Matter in UK Health
In the UK, weight is commonly expressed in stone and pounds, while NHS clinical records use kilograms. This dual system can be confusing, which is why a reliable weight calculator is essential. Converting your weight accurately helps you:
- Compare your weight against NHS healthy weight ranges
- Track progress if you're managing your weight
- Communicate accurately with your GP about your health
- Calculate your BMI, a key health screening metric recommended by NICE
- Understand health information from different sources that may use different units
Beyond simple conversion, calculating your BMI alongside your weight gives you a clearer picture of your health status. For UK adults, a BMI between 18.5 and 24.9 is considered healthy by NHS standards, though ethnicity-adjusted thresholds apply for adults of South Asian, Chinese, Black African, or Black Caribbean heritage, who face higher health risks at lower BMI levels.
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.
How to Use a Weight Converter and Calculate Your Healthy Weight Range
Start by entering your current weight—whether in kilograms, stone, or pounds—into our free weight converter on this page. The tool will instantly display your weight in all three measurements, making it easy to understand how your weight translates across different systems. Next, use our BMI calculator to find your BMI number. Simply enter your height and weight, and the calculator shows your BMI result and which NHS category you fall into: healthy weight, overweight, obese, or severely obese.
To find your healthy weight range for your height, the NHS recommends a BMI between 18.5 and 24.9. If you're concerned about your weight or have weight-related health conditions, your GP can provide personalised advice about what your results mean for your individual circumstances.
Regular weight tracking is important for long-term health management. If you're working toward weight loss or managing a weight-related condition like type 2 diabetes or high blood pressure, tracking your progress over time helps you stay motivated and identify what's working. Our free progress tracker allows you to log your weight regularly, see trends, and visualise your progress toward your goals. Combined with NHS health guidance on nutrition and physical activity, consistent tracking creates accountability and helps you make informed decisions about your health.
- 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's the difference between stone, pounds, and kilograms?
Stone and pounds are imperial units commonly used in the UK for body weight. One stone equals 14 pounds exactly. Kilograms are metric units used in NHS clinical records and most of the world. One kilogram equals approximately 2.2 pounds. Our weight converter handles all these conversions instantly.
How do I calculate a healthy weight range for my height?
Use the BMI formula: BMI = weight (kg) ÷ height (m)². A healthy BMI is 18.5–24.9 according to NHS guidelines. For your specific height, multiply 18.5 and 24.9 by your height squared to get the lower and upper healthy weight bounds in kilograms.
Why does ethnicity matter for BMI categories?
Adults of South Asian, Chinese, Black African, and Black Caribbean heritage have higher cardiovascular and diabetes risk at lower BMI levels. The NHS recommends lower BMI thresholds for these groups: healthy weight is 18.5–22.9 instead of 18.5–24.9, reflecting their individual health risk profiles.
What should I do if my BMI shows I'm overweight or obese?
Start by speaking with your GP, who can assess your individual health and discuss options. This might include lifestyle changes like improved nutrition and activity, referral to NHS weight management services, or in some cases, prescription weight management support alongside lifestyle changes.
Can I use a weight calculator to track weight loss progress?
Yes. Use our weight converter to monitor your weight in familiar measurements, and our progress tracker to log regular weigh-ins. Tracking alongside a reduced-calorie diet and increased physical activity helps you see progress and stay motivated. Aim for sustainable loss of around 0.5–1 kg per week.
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.