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 Average Weight by Age in the UK?
Average weight varies significantly by age group across the UK population. According to the latest Office for National Statistics (ONS) data, UK adults range widely in weight, with averages typically increasing with age until around 65 years old, then stabilising or declining slightly. However, what matters more than comparing yourself to an average is understanding whether your weight falls within a healthy range for your individual height using NHS guidance. Our free BMI calculator above can help you assess your personal weight status instantly, regardless of age.
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.
UK Average Weights by Age Group
Latest ONS data shows these approximate average weights for UK adults:
- Ages 18–24: Women approximately 68 kg (10st 10lbs), Men approximately 78 kg (12st 3lbs)
- Ages 25–34: Women approximately 71 kg (11st 2lbs), Men approximately 82 kg (12st 13lbs)
- Ages 35–44: Women approximately 73 kg (11st 6lbs), Men approximately 84 kg (13st 3lbs)
- Ages 45–54: Women approximately 75 kg (11st 11lbs), Men approximately 85 kg (13st 5lbs)
- Ages 55–64: Women approximately 75 kg (11st 11lbs), Men approximately 84 kg (13st 3lbs)
- Ages 65+: Weight tends to remain stable or decrease slightly
These figures include all body compositions and heights, so they are averages only. The average UK adult man weighs approximately 85.7 kg (13st 7lbs) overall, whilst the average woman weighs approximately 71.6 kg (11st 3lbs). However, being at or near the average does not necessarily mean your weight is healthy for your individual height and body composition.
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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.
Why Healthy Weight Matters More Than Average
NHS health guidance emphasises that a healthy weight is personal to you. Rather than aiming for an average, your healthy weight range depends on your height, age, sex, and muscle mass. The NHS healthy weight range is a BMI between 18.5 and 24.9, though for adults of South Asian, Chinese, Black African, or Black Caribbean backgrounds, the NHS recommends slightly lower thresholds (BMI 18.5–22.9) due to higher health risks at the same BMI. Use our free weight converter to check your weight in stone, lbs, or kg, then calculate your personal BMI using the calculator on this page. If you have concerns about your weight or health, your GP can provide personalised guidance based on your individual circumstances, medical history, and goals.
- 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.
Is my weight healthy if it's close to the average for my age?
Not necessarily. Average weight varies widely by height and body composition. Two people aged 40 can have the same weight but very different BMIs depending on their height. Use the BMI calculator on this page with your actual height to get a personalised assessment. Your GP can advise whether your weight is healthy for you specifically.
Why does weight tend to increase with age?
Several factors contribute: muscle mass naturally declines with age (muscle weighs more than fat), metabolism slows, activity levels may decrease, and hormonal changes occur. However, weight gain is not inevitable. Staying physically active and maintaining muscle mass can help stabilise weight as you age.
What's considered overweight or obese according to NHS guidance?
According to the NHS, a BMI of 25.0–29.9 is overweight, and 30.0 and above is obese. However, these thresholds are lower for South Asian, Chinese, Black African, and Black Caribbean adults (overweight starts at BMI 23.0). Calculate your BMI instantly using the free calculator on this page.
Should I try to weigh less than the average if I'm above it?
Not automatically. Weight loss should be based on your individual health needs, not population averages. The NHS recommends losing weight at a sustainable rate of 0.5–1 kg per week if advised by your GP. Our progress tracker can help you log any weight management journey you undertake with professional guidance.
How do I find my healthy weight range for my height?
Your healthy BMI range is 18.5–24.9 (or 18.5–22.9 for South Asian, Chinese, Black African, or Black Caribbean adults). Calculate your personal healthy weight range using our free BMI calculator above, which instantly shows the weight range that corresponds to a healthy BMI for your height.
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.