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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Calculate Weighting: A UK Guide to Healthy Weight Assessment
"Calculate weighting" refers to assessing your body weight in relation to your height and overall health status. In the UK, this is typically done using BMI (Body Mass Index) alongside NHS guidance on healthy weight ranges. Your weighting is not just a number — it's a health indicator that helps you and your GP understand whether your weight is in a healthy range for your age, height, and background. This guide explains how to calculate weighting, what the results mean, and how to use that information to support your health.
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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 Your Weighting Using BMI
The most straightforward way to calculate weighting is using Body Mass Index (BMI), the standard measurement recommended by the NHS and health professionals worldwide. BMI is calculated by dividing your weight in kilograms by your height in metres squared: BMI = weight (kg) ÷ height (m)².
- Healthy weight BMI: 18.5 to 24.9 (for most UK adults)
- Overweight BMI: 25.0 to 29.9
- Obese BMI: 30.0 and above
However, BMI is not perfect — it doesn't distinguish between muscle and fat, so athletes may have a high BMI with low body fat. For a more complete picture, also measure your waist circumference. For men, increased risk starts at 94 cm (37 inches); for women, at 80 cm (31.5 inches). Use our free BMI calculator on this page to find your BMI instantly, or the weight converter to switch between stone, kilograms, and pounds.
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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.
What Your Weighting Result Means for Your Health
Once you've calculated your weighting, the NHS provides clear guidance on what your result means. If your BMI falls in the healthy range (18.5–24.9), you're at lower risk for weight-related health conditions. A BMI in the overweight range (25.0–29.9) suggests you may benefit from lifestyle changes — increased physical activity and modest dietary adjustments can significantly improve your health outcomes. If your BMI is 30 or above, NHS guidance recommends discussing weight management options with your GP, which may include behaviour change support, dietary advice, or in some cases, prescription weight management medication. Remember, ethnicity matters: if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds because these groups face higher health risks at lower weights.
- 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 difference between calculating weighting and calculating BMI?
"Weighting" is a general term for assessing your body weight in health context. BMI is the specific calculation method most commonly used. BMI = weight (kg) ÷ height (m)². Both terms are used interchangeably in UK health information, but BMI is the formal NHS measurement.
Why does ethnicity affect how I should calculate my weighting?
Research shows that people of South Asian, Chinese, Black African, and Black Caribbean heritage have higher risk of type 2 diabetes and cardiovascular disease at lower BMI levels. The NHS recommends lower BMI thresholds for these groups — typically 18.5–22.9 for healthy weight, compared to 18.5–24.9 for other populations.
Is BMI the only way to calculate weighting?
BMI is the most widely used and recommended method, but it's not perfect. Other measurements include waist circumference, waist-to-height ratio, and body composition analysis. For a fuller picture, combine BMI with waist measurement — increased health risk starts at 94 cm for men and 80 cm for women.
Can I calculate my weighting if I'm pregnant or very muscular?
BMI is less accurate during pregnancy and for very muscular individuals (including athletes). If you're pregnant, discuss your weight with your midwife or GP rather than relying on BMI alone. For muscular adults, consider body composition or waist-to-height ratio as additional context.
How often should I calculate my weighting?
The NHS suggests monitoring your weight every 1–2 weeks as part of a weight management programme. However, daily weighing can be unhelpful due to natural fluctuations. Monthly or quarterly assessments are reasonable for general health tracking. Use our free progress tracker to log changes over time.
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.