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
BMI Chart in Kilos — NHS Weight Categories Explained
A BMI chart in kilos shows where your weight falls according to NHS health standards. The BMI formula divides your weight in kilograms by your height in metres squared, producing a number that fits into NHS categories: underweight, healthy weight, overweight, obese, or severely obese. Understanding your BMI range is the first step toward making informed health decisions. This guide explains the NHS BMI categories and what they mean for your health, using the metric measurements UK clinicians rely on.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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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 recommends these BMI ranges for adults:
- Below 18.5 — Underweight. May indicate nutritional concerns; discuss with your GP if you're consistently below this range.
- 18.5 to 24.9 — Healthy weight. This is the target range for most adults according to NHS guidelines.
- 25.0 to 29.9 — Overweight. Health risks begin to increase at this level; weight management may be recommended.
- 30.0 to 34.9 — Obese (Class I). Increased risk of type 2 diabetes, heart disease, and other conditions.
- 35.0 to 39.9 — Obese (Class II). Significant health risks; GP discussion recommended.
- 40.0 and above — Severely obese (Class III). High health risks; specialist assessment usually recommended.
Important: For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds due to higher health risks at lower BMI levels. For these groups, healthy weight is 18.5 to 22.9, and obesity starts at 27.5 or above.
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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 and When to Seek Support
If your BMI falls outside the healthy range, the NHS offers support through a structured weight management pathway. Tier 1 includes self-help tools and community programmes accessible through your GP. Tier 2 offers primary care behaviour change support. Tier 3 provides specialist multidisciplinary weight management services, which may include prescription weight loss treatments for eligible adults. Your GP can assess your individual health and refer you to appropriate support. Remember, BMI has limitations — it doesn't account for muscle mass or fat distribution. Waist circumference and overall health context matter too. Use our free BMI calculator above to find your personal BMI and explore what it means for your health.
- 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 the BMI formula in kilos?
BMI = weight (kg) ÷ height (metres)². For example, if you weigh 75kg and are 1.75m tall: 75 ÷ (1.75 × 1.75) = 75 ÷ 3.06 = BMI of 24.5 (healthy weight). Use our free BMI calculator to compute yours instantly.
What BMI range is considered healthy by the NHS?
According to NHS guidelines, a healthy BMI is 18.5 to 24.9 for most adults. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the healthy range is 18.5 to 22.9 due to higher disease risks at lower BMI levels.
Is BMI the only measure of health?
No. BMI is a useful screening tool but has significant limitations. It doesn't distinguish between muscle and fat, doesn't account for fat distribution, and may be less accurate for older adults or very muscular individuals. Waist circumference and overall health are also important considerations your GP can discuss.
What should I do if my BMI is in the overweight range?
If your BMI is 25 to 29.9, speak to your GP about weight management options. Small changes in diet and activity can help. The NHS offers tier 1 and tier 2 support programmes. Your GP can assess whether referral to specialist services is appropriate.
How do I know if I need referral to NHS specialist weight services?
Generally, referral to tier 3 specialist weight management services is considered for BMI ≥30, or BMI 27–29.9 with weight-related health conditions (diabetes, high blood pressure, sleep apnoea). Your GP will assess your individual circumstances and discuss options with 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.