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 Calculation: A Complete UK Health Guide
Weight calculation is essential for understanding your health and monitoring progress towards your goals. Whether you need to convert between kg, stone, and pounds, or calculate your healthy weight range according to NHS guidance, getting the right measurements is the first step. This guide explains how to calculate weight accurately, interpret the results, and use our free tools to support your health management journey.
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.
How to Calculate Weight and Convert Between Units
Weight calculation involves converting between the three main units used in the UK: kilograms (kg), stone, and pounds (lbs). The most common conversions are:
- Kilograms to stone: Divide your weight in kg by 6.35029. For example, 70 kg ÷ 6.35 = 11 stone (approximately).
- Kilograms to pounds: Multiply your weight in kg by 2.20462. So 70 kg × 2.20 = 154 lbs.
- Stone to pounds: Multiply the stone value by 14. One stone always equals exactly 14 pounds.
Most UK adults use stone and pounds for body weight, whilst the NHS and healthcare professionals use kilograms for clinical measurements. Our free weight converter above lets you calculate instantly between all three units without needing to remember formulas. This is especially useful when comparing your weight against NHS health guidance or tracking your health metrics over time.
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.
Calculating Your Healthy Weight Range Using NHS Thresholds
Your healthy weight range depends on your height and is determined using BMI (Body Mass Index). According to NHS guidance, a healthy BMI is between 18.5 and 24.9. To calculate your healthy weight range, multiply your height in metres squared by 18.5 (lower bound) and 24.9 (upper bound). For example, if you're 1.73m tall: lower bound = 18.5 × (1.73)² = 55.4 kg (8st 10lbs), upper bound = 24.9 × (1.73)² = 74.5 kg (11st 10lbs). For South Asian, Chinese, Black African, or Black Caribbean adults, the NHS recommends slightly lower thresholds starting at 18.5 to 22.9, as these groups face higher health risks at lower BMI levels. Use our free BMI calculator above to discover your personal BMI and healthy weight range instantly.
- 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 BMI and actual weight?
Weight is the actual force gravity exerts on your body (measured in kg or stone). BMI combines weight with height to assess whether your weight is healthy for your height. Two people at the same weight can have different BMIs if they have different heights. BMI doesn't account for muscle mass, so athletes may have a high BMI but healthy body composition. Use our BMI calculator to check both your weight and BMI in context.
How do I calculate if I'm a healthy weight?
First, calculate your BMI using your weight and height. According to NHS guidance, a BMI between 18.5 and 24.9 is healthy. You can also calculate your healthy weight range by multiplying your height in metres squared by 18.5 and 24.9. For example, at 1.75m tall, healthy weight is approximately 56–76 kg (8st 12lbs to 12st). If you're unsure, your GP can give personalised advice.
Why do UK health guides use kg but people weigh themselves in stone?
The NHS and clinical services use kilograms for consistency and precision in medical records. However, UK culture and most bathroom scales still use stone and pounds for personal use. This is historical — the UK historically used imperial measurements. Today, UK health advice uses both: NHS uses kg, but GPs understand when patients describe their weight in stone. Our weight converter helps you switch between both.
Can I calculate weight loss if I'm on Mounjaro or Wegovy?
Weight loss from medications like Mounjaro and Wegovy varies significantly between individuals. Clinical trials showed average weight loss of 15–21% body weight with Mounjaro and approximately 15% with Wegovy, but individual results depend on many factors. Our GLP-1 weight loss calculator can help estimate potential outcomes at different doses. Always discuss realistic expectations with your prescriber — weight loss is best supported by both medication and lifestyle changes.
What's the best way to track my weight calculations over time?
Consistent tracking helps you spot trends and stay motivated. Record your weight weekly (not daily, as natural fluctuation can be 1–2 kg). Use the same time of day, ideally after using the toilet and before eating. Our free progress tracker on this site lets you log your weight in kg, stone, or lbs and visualise your progress automatically — all completely private and stored only on your device.
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.