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 Check — Your UK Health Guide
A weight check is a simple assessment of whether your current weight falls within a healthy range for your height and age. In the UK, this is typically done using your BMI (body mass index) and NHS health guidelines. Understanding your weight in relation to your health is the first step toward making informed decisions about your wellbeing. Our free BMI calculator and weight converter above can help you check your weight instantly and see where you stand according to UK health standards.
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 BMI Categories
In the UK, the NHS uses BMI as a screening tool to assess whether you're at a healthy weight. A healthy weight is defined as a BMI between 18.5 and 24.9. The NHS weight categories are:
- Underweight: BMI below 18.5
- Healthy weight: BMI 18.5–24.9
- Overweight: BMI 25.0–29.9
- Obese (Class I): BMI 30.0–34.9
- Obese (Class II): BMI 35.0–39.9
- Severely obese (Class III): BMI 40.0 and above
If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds—a healthy weight is 18.5 to 22.9. This is because these populations face higher health risks at lower BMI levels. Use our BMI calculator on this page to find your personal BMI and see which category applies to you.
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.
UK Tools and Resources for Weight Management
Several free NHS and independent tools are available to help you manage your weight in the UK. Our free weight converter on this page lets you switch between kilograms, stone, and pounds instantly—essential for UK health guidance. The NHS Weight Loss Plan is available free through the NHS website and offers a structured 12-week programme. Your GP can refer you to a local weight management service if you need additional support. For those interested in weight loss medication options, our GLP-1 weight loss calculator can help you explore potential outcomes with evidence-based treatment. Weight management is a journey—tracking progress using our free progress tracker can help you stay motivated and see real changes 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 exactly is a weight check?
A weight check is an assessment of whether your weight is healthy for your height and age, usually measured using BMI. In the UK, it's based on NHS guidelines and health thresholds. Your GP can perform a weight check as part of routine health monitoring, or you can check your own BMI using our free calculator on this page.
How do I know if I'm at a healthy weight in the UK?
The NHS defines healthy weight as a BMI between 18.5 and 24.9. However, BMI has limitations—it doesn't account for muscle mass or fat distribution. Your GP can provide personalised advice about what a healthy weight means for you, considering your individual health, age, and medical history.
Should I be concerned if my BMI is in the overweight category?
Being in the overweight category (BMI 25–29.9) means your health could benefit from weight management, but it's not an emergency. Many people live healthily in this range. If you have weight-related health conditions like high blood pressure or type 2 diabetes, your GP may recommend lifestyle changes or support services.
What's the difference between weight check and weight management?
A weight check is a one-time assessment of your current weight status. Weight management is an ongoing process involving diet, physical activity, and sometimes medical support to reach and maintain a healthy weight. A weight check is usually the starting point for weight management.
Can my GP help me with a weight check?
Yes, your GP can perform a weight check as part of your annual health check or at any appointment. They can calculate your BMI, discuss your health risks, and refer you to NHS weight management services if needed. Many GP practices now offer structured weight management programmes through tier 2 services.
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.