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
Am I Overweight? How to Check Using NHS Guidelines
Whether you're overweight depends on your height, age, and overall health—not just a number on the scales. The most reliable way to check is by calculating your BMI (Body Mass Index) using NHS guidance. A healthy BMI for most UK adults is between 18.5 and 24.9, while 25 to 29.9 is classed as overweight. However, BMI is just one piece of the picture. Your GP can provide personalised health advice based on your individual circumstances, medical history, and weight-related health conditions. Use our free BMI calculator above to check where you stand right now.
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 Calculate Your Healthy Weight Range
Your healthy weight range depends entirely on your height. The NHS provides clear guidance: a healthy BMI sits between 18.5 and 24.9 for most adults. To find your personal healthy weight range, multiply your height in metres by itself, then multiply by 18.5 (lower bound) and 24.9 (upper bound).
For example, if you're 1.75m tall (5ft 9in), your healthy weight range is approximately 55kg to 76kg (8st 9lbs to 12st).
If you fall into the 25–29.9 BMI range, you're classified as overweight. A BMI of 30 or above is classed as obese. However, important context: BMI doesn't account for muscle mass, where fat is stored, or your individual health profile. Athletes may have a high BMI but low body fat. Your GP can assess what your weight means for your specific health using the free weight converter and BMI tools available on this page.
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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 Being Overweight Means for Your Health
Being overweight increases your risk of type 2 diabetes, high blood pressure, heart disease, and certain cancers. Even modest weight loss—just 5-10% of your current weight—can significantly improve these health markers and boost your energy and mood.
If your BMI is above 25, your GP may discuss weight management with you. This might include dietary changes, increased physical activity, or in some cases, prescription weight loss support. Access to weight management services varies across NHS regions, so ask your GP about local tier 3 specialist services in your area. You can also track your progress using our free progress tracker to monitor 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's the difference between overweight and obese?
According to NHS guidelines, overweight is a BMI of 25–29.9, whilst obese is 30 or above. Obese is further divided into Class I (30–34.9), Class II (35–39.9), and Class III (40+). However, BMI is just one health indicator—your GP considers your overall health picture too.
Is BMI accurate for everyone?
BMI is a useful screening tool but has limitations. It doesn't distinguish muscle from fat, doesn't account for where weight is stored, and may be less accurate for very muscular people, older adults, or those with certain conditions. Your GP can provide more personalised assessment.
What if I'm overweight but feel healthy?
Many overweight people feel well, but excess weight still increases health risks over time—even without noticeable symptoms now. It's worth discussing your individual risk factors with your GP, who can advise whether weight management would benefit your long-term health.
How much weight do I need to lose to be healthy?
Losing just 5–10% of your body weight can improve blood pressure, blood sugar, and cholesterol. You don't need to reach a "perfect" weight—meaningful health improvements happen with modest, sustainable loss. Your GP can help set realistic targets for you.
Where can I get help with weight management in the UK?
Start by speaking to your GP about NHS weight management services available in your area. Many regions offer tier 3 specialist services combining diet, activity, and sometimes medication. Private weight loss support and prescription options are also available—your GP can advise what's right for you. ```
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.