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 Your Ideal Height and Weight?
There's no single "ideal" weight — it depends on your height, age, muscle mass, and overall health. In the UK, we use NHS health guidance to determine healthy weight ranges based on BMI (body mass index) and individual circumstances. Rather than chasing a number on the scales, the focus is on reaching a weight that supports good health and reduces risk of weight-related conditions. Your GP can help you understand what a healthy weight looks like for you personally.
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 recommends a healthy BMI between 18.5 and 24.9 for most UK adults. This translates to different weight ranges depending on your height. For example, at 5ft 8in (173cm), a healthy weight range is approximately 9st 2lbs to 12st 4lbs (58–78kg). For someone 5ft 4in (163cm), the healthy range is around 8st 0lbs to 10st 11lbs (50–68kg). However, these ranges are not one-size-fits-all.
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds: a healthy BMI between 18.5 and 22.9. This is because these populations face higher health risks from excess weight at lower BMI levels. Your GP can assess your personal circumstances, including family history, existing health conditions, and lifestyle, to discuss what weight range makes sense for you.
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 Picture
BMI is a useful screening tool, but it has important limitations. It doesn't distinguish between muscle and fat — athletes or people with high muscle mass may have a high BMI but low body fat. BMI also doesn't account for where fat is stored (belly fat carries higher health risks) or age-related muscle loss. For a more complete picture, your GP might also assess your waist circumference: men should aim for under 94cm (37in), women under 80cm (31.5in). Use our free BMI calculator above to check your personal BMI, and combine it with the weight converter to see your ideal range in stone and pounds — then discuss the results with your GP for personalised health advice.
- 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 should I aim for at my height?
There's no single "ideal" weight — it depends on your height, age, muscle mass, and health. Use our BMI calculator to find your healthy weight range (BMI 18.5–24.9 for most adults, or 18.5–22.9 for South Asian and other specified ethnic groups). Your GP can give you personalised advice based on your individual circumstances.
How do I know if my weight is healthy?
Check your BMI using our free calculator on this page. A BMI between 18.5 and 24.9 is considered healthy by the NHS. You can also measure your waist circumference: under 94cm (37in) for men, under 80cm (31.5in) for women. Your GP is the best source for personalised health advice.
Is BMI the best way to measure health?
BMI is useful but has limitations — it doesn't account for muscle mass, fat distribution, or age. A more complete health picture includes waist circumference, fitness level, and overall lifestyle. Discuss your weight and health with your GP, who can assess your individual risk factors.
What if I'm overweight but feel healthy?
Weight is just one health marker. However, being overweight (BMI 25–29.9) increases risk of type 2 diabetes, heart disease, and other conditions — even if you feel well now. Losing even 5–10% of your body weight can significantly reduce these risks. Your GP can advise on safe, sustainable weight management.
How can I reach a healthy weight for my height?
The NHS recommends losing weight at 0.5–1kg (1–2lbs) per week through a reduced-calorie diet and increased physical activity. Our weight loss calculator can help you explore realistic targets. For personalised support, ask your GP about NHS weight management services in your area, or use our progress tracker to log your journey.
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.