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
How Heavy Should I Be? Find Your Healthy Weight
Your healthy weight depends on your height, age, and body composition — not just a single number. The NHS defines a healthy weight using BMI (body mass index), which typically falls between 18.5 and 24.9. Using our free BMI calculator above, you can discover your personal healthy weight range in just seconds. However, healthy weight isn't one-size-fits-all: genetics, muscle mass, frame size, and ethnicity all play important roles. Your GP can give you personalised guidance on what weight is right for you.
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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.
Healthy Weight Range by Height (UK Measurements)
The healthy weight range for your height is calculated using BMI 18.5–24.9. Here's what this means across common UK heights:
- 5ft 1in (155cm): 47–63kg (7st 5lbs–9st 13lbs)
- 5ft 3in (160cm): 50–67kg (7st 12lbs–10st 7lbs)
- 5ft 5in (165cm): 53–71kg (8st 5lbs–11st 2lbs)
- 5ft 7in (170cm): 56–76kg (8st 11lbs–11st 13lbs)
- 5ft 9in (175cm): 59–80kg (9st 4lbs–12st 8lbs)
- 5ft 11in (180cm): 63–85kg (9st 13lbs–13st 5lbs)
- 6ft (183cm): 66–89kg (10st 5lbs–14st 0lbs)
These ranges apply to most UK adults. Calculate your exact healthy weight range using the free BMI calculator on this page — it will give you your personal targets in both stone and kilograms. Remember: these are guidelines, not targets everyone must hit.
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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.
Individual Factors That Affect Your Ideal Weight
Your ideal weight isn't just about BMI. Several factors affect what a healthy weight means for you personally:
- Muscle mass: Muscle weighs more than fat. Athletes may have a higher weight but lower body fat percentage and excellent health.
- Frame size: Naturally larger-framed people can healthily weigh more than smaller-framed individuals at the same height.
- Age: Metabolism changes with age; what's healthy at 25 may differ slightly at 55.
- Ethnicity: The NHS recommends lower BMI thresholds for South Asian, Chinese, Black African, and Black Caribbean adults due to higher health risks at the same BMI.
Your weight is just one health marker. Your GP considers your overall fitness, blood pressure, blood sugar, and how you feel when assessing your personal health.
- 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's the difference between healthy weight and ideal weight?
Healthy weight refers to a BMI range (18.5–24.9) associated with lower disease risk. Ideal weight is more personal and accounts for your individual frame, muscle, and goals. The NHS uses healthy weight ranges as guidelines, not strict targets. Your GP can help determine what's ideal for you specifically.
Should I aim for the lower or upper end of the healthy weight range?
There's no "best" end of the healthy weight range. Both 18.5 and 24.9 BMI are equally healthy. Choose a weight where you feel energised, maintain good health markers (blood pressure, blood sugar), and can sustain your lifestyle. Use our weight converter to see both your weight in kg and stone to help set realistic targets.
Why does my height affect how much I should weigh?
Taller people have more body surface area to distribute weight. BMI accounts for height using the formula: weight (kg) ÷ height (m)². This is why two people of the same weight can have very different BMIs depending on their height. Calculate your personal BMI using our free tool above.
What if I'm very muscular — does healthy weight still apply?
BMI doesn't distinguish muscle from fat, so very muscular individuals may fall outside the healthy range despite low body fat. If you're athletic or strength-trained, discuss your weight with your GP rather than relying on BMI alone. Body composition matters more than the number on the scale.
How do I know if I should try to reach my healthy weight range?
If your current weight causes health problems (breathlessness, joint pain, poor blood sugar control), working toward a healthier weight may help. However, focus on feeling better rather than hitting a specific number. Start by tracking your progress with our free progress tracker, alongside small sustainable changes to diet and activity.
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.