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
What Is a Normal BMI?
A normal BMI, according to NHS guidance, falls between 18.5 and 24.9. This range is considered healthy for most UK adults and is associated with lower risk of weight-related health conditions. Your BMI is calculated by dividing your weight in kilograms by your height in metres squared. Use our free BMI calculator above to find your personal BMI instantly, and discover whether your weight falls within the healthy range for your height. If you're curious about what your weight converts to in different units, our weight converter can help you switch between kg, stone, and pounds.
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.
Understanding the NHS BMI Categories
The NHS defines BMI categories as follows:
- Below 18.5 = underweight
- 18.5 to 24.9 = healthy weight (normal BMI)
- 25.0 to 29.9 = overweight
- 30.0 to 34.9 = obese (Class I)
- 35.0 to 39.9 = obese (Class II)
- 40.0 and above = severely obese (Class III)
A normal BMI of 18.5–24.9 reflects a weight that is generally associated with good health outcomes. However, BMI is a screening tool and has limitations — it doesn't account for muscle mass, where fat is stored on your body, or individual health factors. For example, athletes may have a high BMI but low body fat. Your GP can provide personalised advice about what your individual BMI means for your health, especially if you have existing health conditions.
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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.
Ethnicity-Adjusted BMI Thresholds
The NHS recognises that people of South Asian, Chinese, Black African, and Black Caribbean heritage have higher health risks at lower BMI levels. For these groups, a normal BMI range is recommended as 18.5–22.9, with overweight starting at 23.0. This adjustment reflects evidence showing these populations are more susceptible to type 2 diabetes and cardiovascular disease at lower BMI levels compared to other groups. If you fall into one of these ethnic groups, discuss your individual health targets with your GP, as your healthy weight range may differ from the standard NHS threshold. Personalised guidance based on your ethnicity and health profile is important for effective weight management.
- 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.
How do I calculate my normal BMI?
Divide your weight in kilograms by your height in metres squared (BMI = weight ÷ height²). For example, if you weigh 70kg and are 1.75m tall, your BMI is 70 ÷ (1.75 × 1.75) = 22.9. Our free BMI calculator on this page does this instantly — just enter your weight and height in your preferred units.
Is a BMI of 24 considered normal?
Yes, a BMI of 24 falls within the normal healthy weight range of 18.5–24.9 according to NHS guidance. This is considered a healthy BMI for most UK adults. However, always consult your GP about your individual health, as BMI is one screening tool among many.
What is the difference between normal BMI and healthy weight?
Normal BMI (18.5–24.9) and healthy weight are essentially the same thing. A healthy weight is one that falls within the normal BMI range for your height. The NHS uses BMI as the primary screening measure, though waist circumference and overall health also matter.
Do I need to lose weight if my BMI is 25?
A BMI of 25 falls into the overweight category (25–29.9) rather than normal BMI. Whether you need to lose weight depends on your individual health, existing conditions, and family history. Your GP can advise you on whether weight loss would be beneficial for your health. Even modest weight loss of 5–10% can have positive health benefits.
Why is normal BMI different for different ethnic groups?
Research shows that South Asian, Chinese, Black African, and Black Caribbean populations have higher risk of type 2 diabetes and heart disease at lower BMI levels. The NHS therefore recommends lower normal BMI thresholds (18.5–22.9) for these groups. This ensures health guidance is evidence-based and appropriate for your individual ethnic and genetic background.
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.