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 and Weigh — UK Health Guidance Explained
"Weight" and "weigh" are often used interchangeably in everyday speech, but understanding what they mean is essential for managing your health in the UK. Weight refers to the measure of how heavy you are—typically recorded in kilograms, stone, or pounds—while "weigh" is the action of measuring that weight. The NHS uses weight measurements alongside other health indicators like BMI to assess whether you're at a healthy weight. Whether you're tracking your weight management progress or preparing for a health check with your GP, knowing how to interpret these measurements is key to taking control of your health.
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.
NHS Weight Guidance and Healthy Weight Ranges
In the UK, the NHS defines a healthy weight based on your BMI (body mass index), which is calculated from your weight and height. For most adults, a healthy BMI falls between 18.5 and 24.9. Your weight is typically measured in kilograms at medical appointments, though many UK adults still think in terms of stone and pounds for personal tracking.
The NHS recommends regular weight monitoring as part of routine health checks. Your GP can assess whether your current weight poses any health risks, considering factors beyond just the number on the scale—such as where fat is distributed around your body, your waist circumference, and any existing health conditions like type 2 diabetes or high blood pressure. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS applies slightly lower BMI thresholds due to higher health risks at lower weights.
- Healthy BMI range: 18.5–24.9
- Overweight: BMI 25.0–29.9
- Obese: BMI 30.0 and above
Use our free BMI calculator above to check your personal BMI instantly and understand where your current weight sits within NHS guidelines.
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.
Tracking Weight and Using UK Health Tools
Regular weight measurement helps you monitor weight management progress over time, whether you're aiming to lose weight, maintain a healthy weight, or support a medical condition. The NHS encourages weighing yourself weekly or monthly rather than daily, as weight naturally fluctuates due to hydration, hormones, and digestive patterns.
MyWeightCheck provides several free tools to support your weight health journey. Our weight converter makes it easy to switch between metric and imperial units—helpful if your GP discusses weight in kilograms but you prefer to track in stone and pounds. For those exploring weight loss options including GLP-1 medication, our GLP-1 weight loss calculator can project potential outcomes. Our progress tracker lets you log weight changes over time and see trends at a glance—an effective way to stay motivated and identify patterns in your weight management approach.
- 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 weight and weigh?
Weight is a noun describing the heaviness of your body, typically measured in kilograms, stone, or pounds. Weigh is a verb meaning the action of measuring weight on a scale. For example: "My weight is 75kg" or "I weigh 75kg."
What does the NHS consider a healthy weight?
The NHS uses BMI (body mass index) to define healthy weight. A BMI of 18.5–24.9 is considered healthy for most adults. Your GP can assess your personal healthy weight range based on your height, existing health conditions, and other individual factors.
Should I weigh myself daily?
The NHS recommends weighing yourself weekly or monthly rather than daily. Daily weight fluctuates naturally due to hydration, food intake, hormones, and digestion. Weekly or monthly measurements give a clearer picture of actual weight trends.
How do I convert my weight between kg and stone?
To convert kilograms to stone, divide by 6.35. For example, 70kg ÷ 6.35 = 11 stone. Our free weight converter on this page does this instantly for any weight value—just enter your measurement and choose your units.
Why might my GP measure weight differently than home scales?
Medical scales are often more precise than home scales and are calibrated regularly. GPs may weigh you at different times of day, in different clothing, or using different equipment. These variations are normal and don't indicate a problem with your weight management.
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.