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
How Can I Tell if I'm a Healthy Weight?
Wondering whether your weight is healthy? The answer depends on several factors including your height, age, and overall health — not just the number on the scales. In the UK, the NHS uses BMI (Body Mass Index) as the primary screening tool to assess healthy weight ranges. Our free BMI calculator can help you check where you stand in seconds. If you have concerns about your weight or health, your GP is always the best starting point for personalised advice.
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 BMI Ranges and What They Mean
The NHS defines healthy weight using Body Mass Index (BMI) categories. A healthy BMI for most UK adults is between 18.5 and 24.9. BMI is calculated by dividing your weight in kilograms by your height in metres squared. Using our free BMI calculator above, you can instantly find your personal BMI and see which category you fall into. However, BMI has important limitations — it does not distinguish between muscle and fat, and does not account for where fat is stored on your body. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds because these groups face higher health risks at the same BMI levels. Your GP can give you context on what your BMI means for your individual health.
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.
Other Important Signs of a Healthy Weight
Beyond BMI, the NHS emphasises waist measurement as an important indicator of health. For men, a waist over 94cm (37 inches) indicates increased health risk; over 102cm (40 inches) indicates high risk. For women, these thresholds are 80cm (31.5 inches) and 88cm (34.5 inches). You should also consider how you feel — energy levels, ability to do daily activities, fitness, and absence of weight-related health conditions like type 2 diabetes or high blood pressure all suggest good health. If you're uncertain, use our free weight converter to check your weight in different units, and speak with your GP about whether your weight is right for you.
- 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 a healthy BMI in the UK?
The NHS defines a healthy BMI as 18.5 to 24.9 for most adults. However, for South Asian, Chinese, Black African, and Black Caribbean people, the healthy range is 18.5 to 22.9 because these groups have higher disease risk at higher BMI levels. Use our free BMI calculator to find your personal BMI instantly.
Is BMI the only way to tell if I'm a healthy weight?
No. BMI is a useful screening tool but has limitations. It doesn't account for muscle mass, where fat is stored, or bone density. Waist measurement, energy levels, fitness, and the absence of weight-related health conditions are also important. Your GP can assess your individual health comprehensively.
What should my waist measurement be?
According to NHS guidance, men should aim for a waist under 94cm (37 inches) for low health risk. Women should aim for under 80cm (31.5 inches). Measurements above these thresholds indicate increased cardiovascular risk even if BMI appears healthy.
How do I work out my healthy weight range for my height?
Your healthy weight range depends on your height and the BMI range 18.5–24.9. For example, at 5ft 8in (173cm), a healthy weight is approximately 55–74kg (8st 10lbs to 11st 9lbs). Use our free BMI calculator or weight converter to find your personal range.
When should I speak to my GP about my weight?
Speak to your GP if you're concerned about your weight, if you've experienced significant recent weight changes, if you have weight-related health conditions (diabetes, high blood pressure), or if you're considering weight management options. Your GP can provide personalised uk health advice and discuss treatment options if needed. ```
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.