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 Normal Body Mass for UK Adults?
Normal body mass refers to a weight range that supports good health for your height and age. In the UK, the NHS defines this using Body Mass Index (BMI), where a healthy range is 18.5 to 24.9. However, normal body mass goes beyond just a single number — it's about maintaining a weight that reduces disease risk and supports wellbeing. Your individual normal weight depends on your height, age, genetics, and muscle mass. Understanding where you sit within these ranges helps you make informed health decisions, whether you're aiming to maintain, lose, or gain weight. Use our free BMI calculator above to check your personal BMI and see how your weight compares to NHS healthy weight ranges.
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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 Categories and Normal Weight Ranges
The NHS defines normal body mass (also called healthy weight) as a BMI between 18.5 and 24.9. This range reflects a weight that statistically reduces your risk of developing conditions like type 2 diabetes, heart disease, and high blood pressure.
- Underweight: BMI below 18.5 — may indicate insufficient nutritional intake or underlying health issues
- Normal weight: BMI 18.5–24.9 — associated with lowest health risks
- Overweight: BMI 25.0–29.9 — increased health risk starts to appear
- Obese: BMI 30.0+ — significantly elevated 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 the upper limit is 22.9, reflecting higher disease risk at the same BMI levels. Convert your weight between kg and stone using our weight converter to find your exact healthy range for your height.
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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.
Beyond BMI: Body Composition and Other Health Measures
Normal body mass is more than just BMI. Body composition — the ratio of muscle to fat — matters significantly. Two people at the same weight and height can have very different health profiles depending on their body fat percentage and lean body mass. Someone with high muscle mass might have a normal BMI but excellent health, whilst body fat percentage provides more nuance than BMI alone.
Other important measures include waist circumference (a predictor of visceral fat) and waist-to-height ratio. The NHS recommends checking your waist measurement too: increased risk starts above 94cm for men and 80cm for women. Your GP can help assess your full health picture, not just a single number.
- 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 weight is considered normal for my height?
This depends on your exact height. For example, at 5ft 8in (173cm), the normal BMI range is roughly 55–74kg (8st 9lbs to 11st 9lbs). Use our free BMI calculator to enter your height and see your personal healthy weight range instantly.
Is normal body mass the same as ideal body weight?
Not quite. Normal body mass is the NHS BMI range (18.5–24.9), whilst ideal body weight considers frame size, muscle mass, and individual health goals. Both are useful — BMI is a screening tool, but your ideal weight depends on you personally. Your GP can advise.
How is body fat percentage different from BMI?
BMI measures weight relative to height only and cannot distinguish between muscle and fat. Body fat percentage measures the actual proportion of fat tissue. Someone very muscular might have a normal BMI but higher body fat percentage than expected. Both measures together give a clearer health picture than BMI alone.
Can I have a normal BMI but unhealthy body composition?
Yes. A normal BMI doesn't assures good health if body fat is concentrated around the abdomen (visceral fat) or if muscle mass is very low. This is why the NHS also recommends checking waist circumference and staying physically active to maintain lean body mass.
How often should I check if my body mass is normal?
The NHS suggests reviewing your weight quarterly as a practical baseline. However, weight fluctuates daily — focus on trends over weeks, not daily changes. Use our free progress tracker to log your weight journey and identify sustainable patterns rather than chasing daily numbers.
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.