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
Health Weight Calculator — Your UK Guide to Healthy Weight
A health weight calculator is a free tool that helps you understand whether your current weight falls within a healthy range for your age, height, and body type. Using NHS guidelines and evidence-based measurements, these calculators assess your BMI (body mass index) and show you your ideal weight range. Whether you're starting a weight management journey, tracking progress, or simply want to understand your health metrics better, having access to accurate UK health information makes it easier to take control of your wellbeing.
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 Health Weight Calculators Work
A health weight calculator uses your height, weight, and sometimes age and sex to calculate your BMI — a key health screening measure recognised by the NHS. The calculator compares your BMI against NHS categories: underweight (below 18.5), healthy weight (18.5–24.9), overweight (25.0–29.9), and obese (30.0 and above). Important: if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds starting at 23.0 for overweight and 27.5 for obese, as these groups face higher health risks at lower BMI levels.
The best health weight calculators also show your personalised healthy weight range in both kg and stone — the standard UK measurement. Our free BMI calculator on this page instantly shows your BMI category and what a healthy weight range looks like for your specific height, helping you understand your starting point clearly.
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.
Using Health Information to Support Weight Management
Understanding your health metrics is the foundation of sustainable weight management. Whether you're considering lifestyle changes, exploring weight loss options, or simply monitoring your health, having accurate baseline measurements matters. Our GLP-1 weight loss calculator can help estimate potential outcomes if you're exploring prescription weight loss options like Mounjaro or Wegovy, while our weight converter lets you track your progress across kg, stone, and pounds — whichever unit you prefer.
Remember that BMI is a useful screening tool but has limitations — it doesn't account for muscle mass or where fat is stored. Your GP can provide personalised guidance about what your individual metrics mean for your health and any steps you might take next.
- 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 is a healthy weight for my height?
A healthy weight range depends on your individual height, age, and body composition. Use our free BMI calculator above to find your personalised healthy weight range in both kg and stone. The NHS considers a BMI of 18.5–24.9 healthy for most adults, though lower thresholds apply for people of South Asian, Chinese, Black African, or Black Caribbean heritage.
Is BMI the only measure of health?
BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat, so athletes may have a high BMI but low body fat. Waist circumference and overall fitness are also important. Your GP can assess your individual health picture beyond just BMI.
Can a health weight calculator tell me if I need to lose weight?
A health weight calculator shows whether your BMI falls within NHS categories, but it doesn't provide personalised medical advice. If you're concerned about your weight or health, speak to your GP. They can discuss your individual situation, health risks, and any support or treatment options that might help.
How often should I use a health weight calculator?
You can use a health weight calculator as often as you like for monitoring, but meaningful changes typically take weeks or months. Monthly or quarterly checks help track progress. Our free progress tracker lets you log your weight over time and see trends visually.
What's the difference between a health weight calculator and a weight loss calculator?
A health weight calculator shows your current BMI and healthy weight range. A weight loss calculator (like our GLP-1 calculator) estimates potential weight loss with specific interventions like prescription medication, combined with diet and exercise changes. Both are useful for different purposes.
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.