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 the Normal BMI Range According to NHS Guidance?
According to NHS guidance, the normal or healthy BMI range for UK adults is between 18.5 and 24.9. This range applies to most adults regardless of gender, though ethnicity-specific thresholds are recommended for certain populations. Your BMI is calculated using the BMI formula: weight in kilograms divided by your height in metres squared. Understanding where your BMI falls helps you assess whether your current weight poses any health risks. Use our free BMI calculator above to check your personal BMI instantly and see which category you fall into.
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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 What They Mean
The NHS classifies adult BMI into five main categories that determine health risk levels:
- Underweight: BMI below 18.5 — associated with nutritional deficiency risks
- Healthy weight (normal BMI): BMI 18.5–24.9 — lowest health risk range
- Overweight: BMI 25.0–29.9 — increased health risks begin
- Obese (Class I): BMI 30.0–34.9 — significant health risks
- Obese (Class II): BMI 35.0–39.9 — very high health risks
- Severely obese (Class III): BMI 40.0 and above — severe health risks
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — a healthy BMI starts at 18.5 but extends only to 22.9, with overweight beginning at 23.0. This reflects evidence that these populations face higher cardiovascular and metabolic risks at lower BMI levels. NICE guidance supports these ethnicity-adjusted ranges as standard NHS practice.
Clinically BackedWeight Loss
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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 (18.5–24.9), the NHS offers free support through its weight management pathway. Starting with Tier 1, your GP can discuss lifestyle changes, refer you to community programmes, or suggest digital tools like our weight converter and BMI calculator for tracking progress. If BMI reaches 30 or above (or 27+ with weight-related health conditions), you may be eligible for referral to Tier 3 specialist weight management services, where prescription support may be considered. The NHS emphasises that healthy weight loss occurs at approximately 0.5–1 kg per week alongside diet and activity changes. Contact your GP for personalised guidance on achieving and maintaining a normal BMI.
- 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 is considered normal in the UK?
According to NHS guidance, a normal or healthy BMI is between 18.5 and 24.9 for most UK adults. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a healthy range of 18.5–22.9 due to higher health risks at higher BMI levels in these populations.
How do I calculate my BMI to see if it falls in the normal range?
BMI is calculated by dividing your weight in kilograms by your height in metres squared. For example, if you weigh 70kg and are 1.73m tall: 70 ÷ (1.73 × 1.73) = BMI 23.4, which falls in the normal range. Use our free BMI calculator on this page to calculate yours instantly.
What are the BMI limitations I should know about?
BMI does not distinguish between muscle and fat — athletes may have a high BMI despite low body fat. BMI also doesn't account for where fat is stored (waist measurement matters), and may be less accurate for elderly people due to muscle loss. Discuss your individual health with your GP rather than relying on BMI alone.
If my BMI is outside the normal range, what should I do?
Contact your GP, who can assess your individual health and offer support. If your BMI is 25–29.9 (overweight), lifestyle changes are typically recommended first. If 30 or above (or 27+ with health conditions), you may be referred to NHS specialist weight management services. Even modest weight loss (5–10%) can improve health.
Does my ethnicity affect what counts as a normal BMI?
Yes. The NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean heritage because these groups face higher health risks at lower BMI levels. For these populations, a healthy BMI range is 18.5–22.9 rather than 18.5–24.9. Your GP can discuss what's appropriate 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.