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
How Do You Estimate Your Weight and Health?
Estimating your current weight and understanding what it means for your health is the first step towards weight management in the UK. Whether you need to convert between kilograms, stone, and pounds, calculate your BMI, or assess your healthy weight range, there are straightforward methods and NHS-aligned tools available to help. This guide explains how to estimate accurately using UK measurements and gives you the context you need to make informed health decisions.
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.
UK Methods for Estimating Weight and Health
In the UK, weight estimation typically involves three key steps. First, measure your current weight accurately using scales calibrated in kilograms, stone, or pounds — all are valid, but kilograms are most precise for health calculations. Second, convert between units if needed using standard conversion formulas: 1 kg equals 2.2 pounds, or 1 stone equals 6.35 kilograms. Our free weight converter above allows you to switch between all three units instantly. Third, calculate your BMI (body mass index) using your weight and height, which gives you an NHS-recognised health screening tool. The NHS recommends healthy BMI ranges of 18.5 to 24.9 for most adults, though lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults (18.5 to 22.9). Use our BMI calculator on this page to find your personal BMI and see where you fall within NHS guidelines.
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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.
Practical Tools and Next Steps for UK Adults
Once you've estimated your weight and BMI, the next step is understanding what it means for your individual health. Our free BMI calculator provides personalised context based on your measurements and heritage background, aligning with NHS guidance. If you're exploring weight management options, our GLP-1 weight loss calculator can help estimate potential outcomes if you're considering prescription weight loss medication. For ongoing monitoring, our progress tracker lets you log weight changes over time and visualise your journey. Always consult your GP or a registered healthcare professional before making significant health decisions — they can assess your individual circumstances, consider your medical history, and provide personalised UK health advice that goes beyond general estimation tools.
- 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 most accurate way to estimate weight in the UK?
Weigh yourself on calibrated scales (preferably in kilograms for precision), at the same time each day, in light clothing. Record your weight in the unit your scales display, then use a weight converter to switch between kg, stone, and pounds. Take the average of several days for a more reliable estimate, as daily weight fluctuates.
How do I know if my estimated weight is healthy according to NHS guidelines?
Calculate your BMI using your weight and height — use our free BMI calculator above. The NHS healthy BMI range is 18.5 to 24.9 for most adults. If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the recommended range is lower at 18.5 to 22.9. Your GP can provide additional context for your individual health.
Can I estimate my BMI without a calculator?
You can calculate it manually using the formula: BMI = weight (kg) ÷ height (m)². However, our free BMI calculator is more accurate and instantly shows you where you fall within NHS categories, so it's worth using rather than a UK pharmacy calculation.
What if my estimated weight seems different from what I expected?
Weight varies daily due to food, water, hydration, hormones, and time of day. Weigh yourself consistently — same time each morning, after using the bathroom, in light clothing — for reliable estimates. Track over two weeks rather than focusing on single measurements.
Should I estimate weight loss on my own, or get professional help?
For general health estimates, free UK tools like our calculators are helpful. However, if you're considering weight loss medication, exploring NHS services, or have health conditions, consult your GP. They can assess whether weight loss is clinically appropriate for you and provide personalised NHS health advice tailored to your circumstances.
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.