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 for Women?
According to NHS guidance, the normal or healthy BMI range for women is 18.5 to 24.9, regardless of age (in adults over 18). This range applies to most women across the UK, though ethnicity-adjusted thresholds exist for certain groups. Your BMI is calculated using the standard BMI formula dividing your weight in kilograms by your height in metres squared. Understanding where you fall within this range helps you assess whether your weight is healthy for your height. Use our free BMI calculator above to check your personal BMI instantly and see which category you fall into.
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 Thresholds for Women
The NHS defines these BMI categories for all adults, including women:
- Underweight: BMI below 18.5
- Healthy weight (normal range): BMI 18.5–24.9
- Overweight: BMI 25.0–29.9
- Obese (Class I): BMI 30.0–34.9
- Obese (Class II): BMI 35.0–39.9
- Severely obese (Class III): BMI 40.0 and above
The healthy BMI range of 18.5–24.9 is based on population health data linking BMI to disease risk. However, BMI has limitations — it does not distinguish between muscle and fat, so athletic women with high muscle mass may have a higher BMI despite low body fat. For South Asian, Chinese, Black African, or Black Caribbean women, the NHS recommends lower thresholds: a healthy range of 18.5–22.9 is recommended, as these groups face higher cardiovascular and diabetes risk at the same BMI. Your GP can discuss whether your individual BMI is appropriate for your circumstances.
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 Support and When to Seek Help
If your BMI falls outside the healthy range, the NHS offers free weight management support through a structured pathway. Your GP can provide initial advice on diet and physical activity, or refer you to a local weight management programme (Tier 2 service) for structured support. If your BMI is 30 or above, or 27–29 with weight-related health conditions like type 2 diabetes or high blood pressure, you may be eligible for specialist weight management services (Tier 3). These services may include behavioural support, medical monitoring, and in some cases prescription weight loss treatment. The NHS recommends losing weight gradually at a rate of 0.5–1 kg per week for sustainable results. Speak to your GP about what support is available in your area, or use our weight converter to understand your weight in different units alongside the BMI calculator.
- 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 a BMI of 20 normal for women?
Yes, a BMI of 20 falls squarely within the NHS healthy weight range of 18.5–24.9 for women. At this level, your weight is considered normal according to NHS guidelines, though individual health depends on many factors beyond BMI alone, including waist circumference, fitness level, and overall lifestyle.
What BMI should a woman aim for?
The NHS recommends aiming for a BMI between 18.5 and 24.9. Within this range, your health risk is lowest based on population data. For women of South Asian, Chinese, Black African, or Caribbean heritage, the NHS suggests aiming for 18.5–22.9. Your GP can advise on a realistic target for your individual circumstances.
Is BMI the only measure of healthy weight for women?
No. While BMI is a useful screening tool, it has significant limitations. The NHS also recommends measuring waist circumference — for women, over 80cm (31.5in) indicates increased health risk, and over 88cm (34.5in) indicates high risk. Fitness level, muscle mass, and overall health also matter.
At what BMI should a woman consider weight loss?
The NHS suggests considering weight loss support if your BMI is 25 or above. If your BMI is 27–29 with weight-related health conditions (diabetes, high blood pressure, sleep apnoea), or BMI 30 or above, your GP may recommend intervention or referral to specialist weight management services.
How do I calculate my BMI as a woman?
Divide your weight in kilograms by your height in metres squared (BMI = weight ÷ height²). For example, a woman weighing 65kg and 165cm tall: 65 ÷ (1.65)² = 23.9 BMI. Our free BMI calculator above does this instantly — just enter your height and weight to see your BMI and category.
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.