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
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How to Calculate BMI for Women
Calculating your BMI (Body Mass Index) is straightforward and takes just a few seconds. BMI is a useful screening tool recommended by the NHS to assess whether your weight falls within a healthy range for your height. The BMI formula is the same for both men and women, though NHS guidance does acknowledge that healthy weight ranges can vary by ethnicity. This guide explains the calculation, what your result means according to NHS standards, and when you should speak to your GP about your weight and health.
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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.
BMI Formula and NHS Categories
The BMI formula is simple: divide your weight in kilograms by your height in metres squared. For example, if you weigh 70 kg and are 1.65 metres tall, your BMI would be 70 ÷ (1.65 × 1.65) = 25.7.
According to NHS BMI categories, the healthy BMI range for most women is 18.5 to 24.9. However, the NHS recognises that women of South Asian, Chinese, Black African, or Black Caribbean heritage face higher health risks at lower BMI levels and recommends a slightly lower threshold of 18.5 to 22.9 for these groups. Use our free BMI calculator above to find your personal BMI instantly — simply enter your weight and height, and the tool will calculate your result and show you which NHS category you fall into.
Key BMI ranges:
- Below 18.5 = Underweight
- 18.5–24.9 = Healthy weight
- 25.0–29.9 = Overweight
- 30.0–34.9 = Obese (Class I)
- 35.0+ = Severely obese
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.
NHS Weight Management and When to Seek Support
If your BMI falls outside the healthy range, the NHS offers a structured weight management pathway to support you. Most people begin with Tier 1 services — self-help resources, digital tools like our free BMI calculator and weight converter, and community weight management programmes. If you need more support, your GP can refer you to Tier 2 (primary care-based behaviour change programmes) or Tier 3 (specialist multidisciplinary services). For women with a BMI of 30 or above, or 27–29.9 with weight-related health conditions, prescription weight loss medications may be considered alongside lifestyle changes. Your GP is the best starting point to discuss your individual health and explore what support is available to 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.
Is the BMI formula different for women than for men?
No, the BMI formula is identical for men and women: weight (kg) ÷ height (m)². However, NHS guidance recognises that women of certain ethnic backgrounds (South Asian, Chinese, Black African, Black Caribbean) have different health risk profiles at the same BMI, so lower thresholds may apply.
What is considered a healthy BMI for women in the UK?
According to NHS guidelines, a healthy BMI for most women is 18.5 to 24.9. For women of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends 18.5 to 22.9. Your GP can advise you on what's healthy for your individual circumstances.
Does BMI account for muscle mass in women?
No — this is a key BMI limitation. BMI does not distinguish between muscle and fat. Athletic women with high muscle mass may have a BMI in the overweight or obese range despite being fit and healthy. Your GP can assess your overall health beyond BMI.
What should I do if my BMI is above the healthy range?
Start by speaking to your GP, who can assess your individual health and discuss weight management options. The NHS offers a stepped approach: self-help resources and community programmes first, then primary care support, then specialist services if needed. Sustainable weight loss of 0.5–1 kg per week is recommended.
Are there other measurements I should consider alongside BMI?
Yes. Waist circumference is important — increased health risk begins at over 80cm for women, high risk at over 88cm. The NHS also considers where fat is stored and other health factors. BMI is a useful screening tool but works best alongside other health assessments from your GP.
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.