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
Optimal Weight Chart for UK Adults
Your optimal weight depends on your height, age, and individual health factors — not a single number. The NHS uses BMI (body mass index) to define healthy weight ranges, though this is just one tool. For most UK adults, a BMI between 18.5 and 24.9 is considered healthy, but the best weight for you is one that supports your overall health and wellbeing. This guide explains how to find your optimal weight range and why it matters for your long-term health.
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.
How to Find Your Optimal Weight Range
Your optimal weight range is calculated based on your height and individual health factors. Use our free BMI calculator above to find your personal healthy weight range instantly.
The NHS defines healthy weight using these BMI categories:
- Underweight: BMI below 18.5
- Healthy weight: BMI 18.5–24.9
- Overweight: BMI 25–29.9
- Obese: BMI 30 and above
For example, if you're 1.73m tall (5ft 8in), your healthy weight range is approximately 55–74 kg (8st 9lbs to 11st 9lbs). However, optimal weight also depends on muscle mass, bone density, and existing health conditions. Your GP can give you personalised advice about what's optimal for your specific circumstances. These ranges are screening tools, not medical targets — the best weight is one where you feel healthy and energised.
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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.
Special Considerations for Optimal Weight
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds because these groups face higher health risks at lower weights. Healthy weight for these populations starts at BMI 18.5–22.9 rather than 18.5–24.9.
Age, fitness level, and genetics also affect your optimal weight. Someone with significant muscle mass may have a higher BMI but excellent health markers. Use our free weight converter to switch between kg, stone, and lbs when checking your range. Regular activity, balanced nutrition, and weight management through sustainable lifestyle changes support long-term health more than chasing a specific number on the scales.
- 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 optimal weight and ideal weight?
Optimal weight is the range that supports your individual health and fitness level, calculated using your height and health factors. Ideal weight is often a single target number, which can be unrealistic. The NHS recommends using BMI ranges rather than single targets — your GP can help you set a realistic, personal goal.
How do I calculate my optimal weight from my height?
A healthy BMI is 18.5–24.9. Multiply your height in metres by itself, then divide your target weight by this number. For example, at 1.75m, a BMI of 18.5 = 56.6kg, and 24.9 = 76.2kg. Use our free BMI calculator above for instant calculations for your exact height.
Is BMI the only measure of optimal weight?
No. BMI doesn't account for muscle mass, bone density, or where fat is stored. Waist circumference is also important — men should aim for under 94cm, women under 80cm. A GP can assess your overall health picture beyond BMI alone.
Can my optimal weight change over time?
Yes. Age, hormonal changes, fitness level, and medical conditions all affect optimal weight. It's normal for weight to fluctuate. Regular check-ins with your GP and use of our free progress tracker help you stay on track with sustainable, personal health goals.
How does weight management fit into finding my optimal weight?
If you're above a healthy range, gradual weight loss of 0.5–1kg per week is sustainable and supported by evidence. Achieving your optimal weight involves balanced nutrition, regular physical activity, and behaviour change — sometimes supported by prescription medications following clinical assessment.
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.