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
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Age by Height Weight Chart — What's a Healthy Weight for You?
There's no single "ideal" weight that applies to everyone, because healthy weight depends on your height, age, sex, and muscle mass. In the UK, the NHS uses BMI (body mass index) as the primary screening tool for healthy weight, rather than age-specific charts. A healthy BMI is between 18.5 and 24.9 for most adults, though lower thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage. Your GP can provide personalised weight management guidance based on your individual health profile, medical history, and lifestyle.
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 Guidance — How to Find Your Range
The NHS doesn't publish separate age-by-height weight charts because BMI is a more reliable health screening tool than age-based tables. BMI accounts for your height, which age-only charts do not. To find your healthy weight range:
- Calculate your BMI using our free BMI calculator on this page — it works for adults of all ages
- A healthy BMI is 18.5–24.9 for most UK adults (lower thresholds apply for South Asian and other heritage groups)
- Multiply your height in metres squared by 18.5 for the lower healthy weight bound, and by 24.9 for the upper bound
- Your GP can discuss whether your current weight is healthy for you, considering your individual circumstances, family history, and any health conditions
Age matters less than overall health — a healthy weight at 30 may differ from a healthy weight at 60 due to muscle loss, medical conditions, and medications, but BMI remains the NHS standard screening method.
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.
UK Tools and Resources to Check Your Healthy Weight
Rather than relying on age-based charts, use NHS-aligned tools to understand your weight health:
- Our free BMI calculator — enter your height and weight to get your BMI category instantly, aligned with NHS thresholds
- Our weight converter — convert between kg, stone, and lbs so you can understand your weight in the units you're comfortable with
- Your GP — the best resource for personalised advice about whether your weight is healthy for your age, health history, and lifestyle
- NHS Health Check — if you're 40–74, you can book a free health check with your practice nurse, which includes weight assessment
If you're concerned about your weight or your child's weight, your GP is the right first step. Specialist weight management services are available through the NHS tier 3 pathway.
- 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.
Why doesn't the NHS use age-by-height weight charts?
The NHS uses BMI instead because it's a more reliable health screening tool. BMI accounts for both your height and weight, whereas age-only charts can be misleading — a healthy weight depends on your individual body composition, muscle mass, and medical history, not just your age.
What's a healthy weight for a 40-year-old who is 5ft 8in?
At 5ft 8in (173cm), a healthy BMI range is 18.5–24.9, which corresponds to roughly 55–74kg (8st 10lbs to 11st 10lbs). However, your GP should assess whether you're at a healthy weight based on your individual health, not age alone. Use our BMI calculator to check your personal BMI.
Are healthy weight ranges different for older adults?
The NHS BMI categories remain the same for older adults (18.5–24.9 is healthy). However, older adults may have different health priorities, and muscle loss with age means BMI can be less accurate. Your GP can discuss what's healthy for you personally, considering your medical history and fitness level.
Why do South Asian adults have lower healthy weight thresholds?
Research shows South Asian, Chinese, Black African, and Black Caribbean adults face higher health risks (type 2 diabetes, heart disease) at lower BMI levels. The NHS recommends a healthy BMI of 18.5–22.9 for these groups, rather than 18.5–24.9. Your GP can discuss the right thresholds for you.
How can I check if my weight is healthy?
Use our free BMI calculator on this page — it takes seconds. A healthy BMI is 18.5–24.9 for most adults. If you'd like personalised advice, especially if you have health conditions or family history concerns, speak to your GP. They can refer you to weight management support if needed.
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.