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 Good BMI Level According to NHS Guidance?
A good BMI level according to NHS guidance is between 18.5 and 24.9, which falls into the healthy weight category. However, the NHS recognises that BMI thresholds vary depending on your ethnicity, age, and individual health circumstances. Understanding your BMI range is an important first step in assessing your health, though BMI alone doesn't tell the whole story about your wellbeing. Our free BMI calculator above can help you find your personal BMI instantly and see where you fall on the NHS scale.
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 Categories and Healthy Weight Ranges
The NHS BMI categories are used across the UK to classify weight status in adults. Here's what the NHS recommends:
- Underweight: BMI below 18.5 — may indicate you need to gain weight for optimal health
- Healthy weight: BMI 18.5–24.9 — the target range the NHS aims to help people achieve
- Overweight: BMI 25.0–29.9 — increased risk of weight-related health conditions
- Obese (Class I): BMI 30.0–34.9 — higher health risks requiring support
- Obese (Class II): BMI 35.0–39.9 — significant health risks
- Severely obese (Class III): BMI 40.0 and above — substantial health risks, NHS intervention often recommended
It's important to note that BMI limitations exist — BMI does not distinguish between muscle and fat, so athletes or very muscular individuals may have a higher BMI but remain very healthy. The NHS uses BMI as a screening tool, not a definitive health measure.
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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.
NHS Weight Management Support and When to Seek Help
If your BMI falls outside the healthy range, the NHS offers a structured weight management pathway. Your GP can assess your individual health risk and discuss options with you, including lifestyle changes, NHS digital weight loss support programmes, and specialist referrals if needed. The NHS recommends losing weight at a rate of 0.5–1 kg per week for sustainable, healthy progress. You can track your weight loss journey using our free progress tracker, which helps you monitor changes over time. If you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions, your GP may refer you to specialist weight management services to discuss all available options.
- 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 BMI range does the NHS consider healthy?
The NHS defines healthy weight as a BMI between 18.5 and 24.9. This range applies to most adults; however, lower thresholds are recommended for people of South Asian, Chinese, Black African, and Black Caribbean heritage due to higher health risks at lower BMI levels.
Is BMI the only measure of good health?
No. The NHS recognises that BMI has limitations. Waist circumference, body composition, fitness level, and overall health markers like blood pressure and cholesterol are equally important. Use our free weight converter and BMI calculator together to get a fuller picture of your health context.
What should I do if my BMI is above the healthy range?
Speak to your GP, who can assess your individual situation and discuss support options. The NHS offers weight management programmes, digital tools, and specialist services. Safe weight loss is typically 0.5–1 kg per week through reduced-calorie diet and increased physical activity.
Do BMI thresholds differ for different ethnic groups?
Yes. The NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean backgrounds. For these groups, the healthy weight range is BMI 18.5–22.9, and overweight begins at 23.0. This reflects higher cardiovascular and metabolic disease risk in these populations.
How do I calculate my BMI?
BMI is calculated as weight (kg) divided by height (metres) squared. Our free BMI calculator on this page does this instantly — just enter your weight and height in either metric or imperial measurements, and it will show your BMI, category, and healthy weight range aligned with NHS guidance.
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.