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
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Accurate Weight Scale — Why Reliability Matters for Health
An accurate weight scale is essential for reliable health tracking and weight management. In the UK, most adults use bathroom scales at home to monitor their weight, but not all scales are equally reliable. Understanding how scales work, what affects accuracy, and how to use them correctly helps you get consistent readings that support your health goals — whether you're tracking progress, calculating your BMI, or working with healthcare professionals. Accuracy matters because even small measurement errors can affect how you assess your health status over time.
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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.
What Makes a Weight Scale Accurate?
A reliable weight scale measures your body mass consistently and without significant variation. Accuracy means the scale shows your true weight, while precision means it gives the same reading repeatedly. Several factors affect both:
- Sensor technology: Digital scales use load cells (electronic sensors) that detect weight; analogue scales use mechanical springs. Digital scales are generally more accurate for home use.
- Calibration: Scales must be calibrated correctly at manufacture. Quality brands recalibrate regularly; cheaper scales may drift over time.
- Surface: Always weigh yourself on a flat, hard, level surface — not carpet or uneven flooring, which introduces measurement error.
- Battery health: Digital scales with weak batteries may display inconsistent results. Replace batteries annually or when readings become erratic.
- Weight capacity: Scales have maximum weight limits. Consistently weighing at or near the limit reduces accuracy.
NHS guidance recommends using the same scale, at the same time of day (morning, before eating), in the same location for consistent tracking. This eliminates variables unrelated to actual weight change.
Clinically BackedWeight Loss
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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.
How to Get the Most Accurate Weight Readings
To ensure reliable measurements, follow these practical steps:
- Weigh yourself in the morning after using the toilet but before eating or drinking — this gives your lowest weight of the day and reduces daily fluctuation from food and water intake.
- Wear the same or similar clothing — clothes can add 0.5–2 kg depending on what you're wearing.
- Use the same scale every time — different scales may show different readings even for the same person, because calibration varies between manufacturers.
- Check the scale is on level ground — uneven surfaces cause significant variation.
- Weigh yourself weekly, not daily — weight naturally fluctuates day-to-day due to water retention, hormones, and digestion. Weekly weighing shows true trends.
Use our free BMI calculator to put your weight measurement into health context, and try our weight converter to switch between kg, stone, and pounds for NHS-recommended tracking. Our progress tracker helps you log weekly weight and spot genuine trends over time.
- 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 accuracy and precision on a scale?
Accuracy means the scale shows your true weight correctly. Precision means it gives the same reading each time you stand on it. A precise scale that's badly calibrated may be consistently wrong. Both matter — look for scales with both high accuracy and good repeatability, usually found in mid-to-premium home scales.
How often should I weigh myself for reliable weight management?
NHS guidance suggests weighing once per week, at the same time and day. Daily weighing is unreliable because weight fluctuates naturally by 1–2 kg due to water, food, hormones, and digestion. Weekly tracking shows real progress; daily tracking creates unnecessary anxiety over normal variation.
Does scale accuracy matter if I'm tracking weight loss with GLP-1 medication?
Yes — consistency is vital. Whether you're using weight loss medication or lifestyle changes, an accurate, consistent scale helps you and your prescriber monitor whether treatment is working. Use the same scale weekly and keep records for your GP or prescriber.
Why do different scales show different weights for the same person?
Calibration varies between manufacturers and models. Even small differences in sensor quality or factory calibration can cause 0.5–1.5 kg variation. Always use one scale for personal tracking. If you switch scales, expect a slight reading change; the actual weight change may be different from the scale difference.
What should I look for when buying an accurate bathroom scale?
Choose digital scales with electronic load cells rather than mechanical springs; they're more stable. Look for brands with good reviews for consistency. Check the maximum weight capacity (ensure you're well below it). Mid-range quality brands (£20–50) offer good accuracy for home use. Avoid very cheap scales under £10 — they often have poor calibration.
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.