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
Understanding Weight Scales and Accurate Measurement
A weight scale is a tool that measures your body weight in kilograms, stone, or pounds. In the UK, most people use stone and pounds for personal weight tracking, though healthcare professionals use kilograms. Accurate weight measurement is an important part of monitoring your health and understanding whether your weight falls within a healthy range according to NHS guidance. Using a reliable scale consistently helps you track progress towards health goals and provides baseline data for discussions with your GP.
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 Use a Weight Scale Accurately
For the most accurate weight readings, weigh yourself at the same time each day — ideally in the morning before eating or drinking, and after using the toilet. Wear minimal clothing to avoid measurement variations. Place your scale on a flat, hard surface, not on carpet or uneven floors, as this affects accuracy. Stand with your weight distributed evenly across both feet in the centre of the scale platform. Wait for the reading to stabilise before recording. Digital scales are generally more accurate than mechanical scales, but both require regular calibration. Most NHS health clinics use calibrated digital scales to ensure consistency. If tracking weight at home, try to use the same scale every time, as different scales may show slightly different readings. Once you know your weight, you can use our free weight converter to switch between kg, stone, and pounds, and our BMI calculator to understand whether your weight falls within a healthy range for your height.
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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.
Weight Scale Readings and Health Context
Your weight alone does not tell the full story about your health. The NHS recommends considering your weight alongside your height to calculate your BMI (Body Mass Index), which provides context about whether you are in a healthy weight range. For UK adults, a healthy BMI is 18.5 to 24.9. Your weight can fluctuate daily due to water retention, food intake, hormonal changes, and time of day — this is normal. Weekly or monthly averages are more meaningful than daily fluctuations. If you are tracking weight loss, aim for a sustainable rate of 0.5 to 1 kg (1 to 2 lbs) per week according to NHS guidance. Sudden large changes in weight (gain or loss of more than 2–3 kg in one week) should be discussed with your GP, as they may indicate underlying health issues.
- 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 the most accurate type of weight scale?
Digital scales are generally more accurate than mechanical scales. For the highest accuracy, use a scale on a hard, flat surface, weigh yourself at the same time daily (ideally morning), and wear minimal clothing. NHS health clinics use calibrated digital scales. If buying a home scale, look for one with a maximum capacity appropriate for your weight and a resolution of at least 0.1 kg (100g).
Should I weigh myself daily or weekly?
Weighing daily is fine, but weekly averages are more meaningful because daily weight naturally fluctuates due to water retention, food, hormones, and time of day. Track daily readings if it motivates you, but focus on weekly or monthly trends rather than day-to-day changes. Use our free progress tracker to log and visualise your weight over time.
What does "water weight" mean?
Water weight refers to temporary changes in body water caused by sodium intake, hormones, exercise, and hydration levels. A sudden 1–2 kg gain often reflects water retention, not fat gain. This typically normalises within a few days. If your weight fluctuates, drink plenty of water and wait a few days before concluding there has been real weight change.
How do I know if my weight is healthy?
Check your BMI using your weight and height. The NHS defines a healthy BMI as 18.5 to 24.9. Use our free BMI calculator on this page to find your personal BMI instantly. Your GP can also advise whether your weight is healthy for you, considering your age, fitness level, medical history, and individual circumstances.
What is a healthy rate of weight loss?
The NHS recommends losing 0.5 to 1 kg (1 to 2 lbs) per week as a sustainable, healthy target. This rate typically requires a calorie deficit of about 500 kcal per day and can be achieved through dietary changes and increased physical activity. Faster weight loss may result in muscle loss and is harder to sustain long-term.
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.