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's the Right Weight for My Height?
Your right weight depends on your height, age, sex, and body composition — there's no single "perfect" number. The NHS uses BMI (Body Mass Index) to define healthy weight ranges, which are evidence-based thresholds linked to health outcomes. For most UK adults, a healthy BMI falls between 18.5 and 24.9. However, ethnicity matters: people of South Asian, Chinese, Black African, or Black Caribbean heritage have higher health risks at lower BMI levels, so the NHS recommends lower thresholds for these groups. Use our free BMI calculator above to find your personal healthy weight range instantly.
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 Healthy Weight Ranges by Height
The NHS defines healthy weight as a BMI between 18.5 and 24.9 for most adults. For South Asian, Chinese, Black African, and Black Caribbean adults, the healthy range is 18.5 to 22.9 due to increased cardiovascular and diabetes risk at higher BMI levels.
To calculate your healthy weight range, multiply your height in metres by itself, then multiply by 18.5 (lower bound) and 24.9 (upper bound). For example, at 5ft 8in (1.73m):
- Lower healthy weight: 18.5 × (1.73)² = 55.4 kg (8st 10lbs)
- Upper healthy weight: 24.9 × (1.73)² = 74.5 kg (11st 10lbs)
- So the healthy range is approximately 8st 10lbs to 11st 10lbs
Use our weight converter to instantly switch between kg, stone, and lbs.
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.
Why BMI Isn't the Whole Story
BMI is a useful screening tool, but it has limitations. It doesn't distinguish between muscle and fat — athletes may have a high BMI but low body fat percentage. BMI also ignores where fat is stored; waist circumference matters. The NHS recommends measuring your waist as part of a complete health picture.
Healthy waist measurements:
- Men: below 94cm (37in); high risk above 102cm (40in)
- Women: below 80cm (31.5in); high risk above 88cm (34.5in)
Your GP can give personalised advice about what weight is right for you, considering your individual health, family history, and lifestyle.
- 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 a healthy weight for a 5ft 6in woman?
At 5ft 6in (168cm), a healthy BMI range (18.5–24.9) corresponds to approximately 47–63 kg (7st 5lbs to 9st 13lbs). However, this is a general guide. Your ideal weight depends on your age, muscle mass, body composition, and overall health. Your GP can advise on what's right for you personally.
Does healthy weight change with age?
Muscle mass naturally decreases with age, and metabolism slows. Some evidence suggests slightly higher healthy BMI ranges may be appropriate for older adults (65+), though guidelines vary. Discuss age-specific healthy weight with your GP, especially if you have existing health conditions.
Is there a healthy weight for someone very tall or very short?
BMI works across all heights, but very tall and very short individuals may find BMI less accurate because it uses a squared height formula. Waist-to-height ratio (waist ÷ height, both in same units) below 0.5 is a good alternative health marker for all heights.
How do I know if I need to lose weight?
If your BMI is 25 or above (or 23+ for South Asian/Chinese/Black African/Caribbean adults), or if your waist circumference exceeds healthy thresholds, your GP may recommend lifestyle changes. Even a 5–clinically studied weight loss can improve blood pressure, blood sugar, and cholesterol. Our BMI calculator shows where you fall on the NHS scale.
Can I use my healthy weight range as a weight loss target?
Yes, aiming for a healthy BMI range (or the lower end if you prefer) is evidence-based. However, sustainable weight loss happens at approximately 0.5–1 kg per week. Our free progress tracker helps you log your journey and stay motivated over time. Always consult your GP before starting a weight loss plan. ```
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.