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 Body Mass Index For A Woman?
A healthy BMI for most women falls between 18.5 and 24.9 according to NHS guidelines. However, your ideal BMI depends on your age, ethnicity, and overall health. Women of South Asian, Chinese, Black African, or Black Caribbean heritage may have a healthy range starting at 18.5 to 22.9, as these groups face higher health risks at lower BMI levels. BMI is one tool to assess health, but it doesn't account for muscle mass or body composition, so it's most useful when considered alongside other health measures like waist circumference and body fat percentage. Using our free BMI calculator above, you can instantly find your personal BMI and see where you fall within the NHS healthy range.
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 Your BMI Results On This Calculator
When you use the BMI calculator on this page, your result will fall into one of five NHS categories. A BMI between 18.5 and 24.9 is considered a healthy weight for most adult women — this range is associated with the lowest risk of weight-related health conditions. If your result shows 25.0 to 29.9, you're in the overweight category, which may increase your risk of type 2 diabetes and cardiovascular disease. A BMI of 30 or above indicates obesity and warrants a conversation with your GP about health management strategies.
For women of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds: a healthy BMI sits between 18.5 and 22.9, with overweight starting at 23.0. This adjustment reflects that these groups experience higher risks of type 2 diabetes and heart disease at lower BMI levels. Your age also matters — younger women typically aim for the standard NHS range, whilst older women may have slightly different targets based on individual health factors. Always discuss your personal BMI results with your GP, as they can consider your complete health picture, including family history, fitness level, and any existing health conditions.
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.
BMI Versus Body Composition — Which Matters More?
BMI is a useful screening tool, but it has real limitations. It doesn't distinguish between muscle mass and fat, so athletes and very fit women may have a high BMI despite low body fat percentage. This is why healthcare professionals often look at body composition — the actual ratio of fat to lean body mass — alongside BMI. Your lean body mass (muscle, bone, organs) is metabolically active and protective of health, whilst excess fat (especially visceral fat stored around organs) carries greater health risks.
For a more complete picture, consider your body fat percentage in addition to BMI. Healthy ranges for women are approximately 21–24% for fitness level and 25–31% for acceptable body composition. You can estimate body fat percentage using a body fat calculator, but DEXA scanning or bioelectrical impedance analysis offer more accuracy. Waist circumference is also important — for women, a waist above 80cm (31.5 inches) suggests increased health risk, and above 88cm (34.5 inches) indicates high risk, regardless of BMI. Use our free weight converter to check your measurements in both metric and imperial units.
- 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 should a woman aim for?
Most women should aim for a BMI between 18.5 and 24.9 according to NHS guidelines. Women of South Asian, Chinese, Black African, or Black Caribbean heritage should aim for 18.5 to 22.9. However, your GP may recommend a slightly different target based on your age, fitness level, medical history, and ethnicity. Always discuss your personal health goals with your healthcare provider.
Is a BMI of 25 overweight for women?
Yes, according to NHS categories, a BMI of 25.0 to 29.9 is classified as overweight. This range suggests an increased risk of type 2 diabetes, high blood pressure, and cardiovascular disease compared to the healthy weight range. However, BMI is just one measure — your GP may recommend lifestyle changes or further health checks based on your individual circumstances.
Can I have a high BMI but still be healthy?
Yes, particularly if you have significant muscle mass from exercise or training. BMI doesn't distinguish between muscle and fat. Athletes often have high BMI despite low body fat percentage. This is why it's valuable to also assess body composition, waist circumference, and cardiovascular fitness. Your GP can help you understand whether your BMI is a health concern for you personally.
How does body fat percentage differ from BMI for women?
BMI measures weight relative to height, whilst body fat percentage measures the actual proportion of fat in your body. A healthy body fat percentage for women is roughly 21–24% (fitness level) to 25–31% (acceptable range). Two women with the same BMI could have very different body fat percentages depending on their muscle mass, making body composition a more nuanced health indicator.
Should I use BMI or waist circumference to assess my health?
Both are useful. BMI gives a general screening measure of whether your weight is healthy for your height. Waist circumference measures visceral fat (fat around organs), which is particularly linked to heart disease and diabetes risk. For women, a healthy waist is under 80cm. Using both measures alongside body fat percentage and discussion with your GP gives the most complete health picture.
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.