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
Weight Calculator UK — Your Free Health Guide
A weight calculator helps you understand where your current weight sits within healthy NHS guidelines and what it means for your health. In the UK, we typically measure weight in stone and pounds, but our free weight calculator works seamlessly with kilograms too. Whether you're curious about your BMI, want to convert your weight between units, or need guidance on healthy weight ranges, this guide covers everything you need plus access to practical UK health tools.
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 Weight Calculators Work in UK Health Context
Weight calculators in the UK serve several purposes. The most common is calculating your Body Mass Index (BMI), which the NHS uses as a screening tool for health risk. BMI is calculated by dividing your weight in kilograms by your height in metres squared. For example, a weight of 70kg at a height of 1.73m gives a BMI of approximately 23.4, which falls in the healthy weight range according to NHS guidelines (18.5–24.9).
A weight calculator also helps you convert between measurement units — essential in the UK where we mix metric and imperial measurements. 70kg equals 11 stone 0.1 lbs. Beyond simple conversion, many UK health calculators provide context: they show you the healthy weight range for your specific height, estimate weight loss projections if you're considering lifestyle changes, and track progress over time.
- BMI calculators assess health risk based on weight and height
- Weight converters translate between kg, stone, and pounds
- Healthy weight range tools show target weight for your height
- Progress trackers monitor weight changes week by week
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.
Free Weight Calculator Tools Available Now
MyWeightCheck provides several free weight calculators designed specifically for UK adults. Our BMI calculator gives you an gradual improvement using your height and weight, plus tells you where you sit on the NHS BMI scale (underweight, healthy, overweight, or obese categories). Our weight converter instantly switches your weight between kilograms, stone, and pounds — no mental maths needed. For those interested in weight management, our GLP-1 weight loss calculator projects potential weight loss if you're considering prescription weight loss medications like Mounjaro or Wegovy.
If you're tracking a weight loss journey, our free progress tracker logs your weight over weeks and months, showing clear trends and celebrating milestones. All tools are free, require no registration, and work on mobile and desktop. Your GP can also provide personalised weight health advice if you have specific health concerns.
- 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 according to NHS guidance?
According to NHS guidelines, a healthy BMI is between 18.5 and 24.9. This corresponds to different weights depending on your height. For example, at 5ft 8in (1.73m), a healthy weight range is approximately 55–75kg (8st 10lbs to 11st 10lbs). However, for adults of South Asian, Chinese, Black African, or Black Caribbean descent, the NHS recommends lower thresholds (BMI 18.5–22.9), as these groups face higher health risks at lower weights.
How do I convert my weight from kilograms to stone?
To convert kilograms to stone, divide the kilogram value by 6.35. For example, 70kg ÷ 6.35 = 11 stone (approximately). You can also use our free weight converter above to switch instantly between kg, stone, and pounds without any a UK pharmacy calculation.
What is BMI and why does the NHS use it?
BMI (Body Mass Index) is a simple screening tool that compares weight to height. It's calculated as weight (kg) ÷ height (m)². The NHS uses BMI because it's a quick way to identify if someone may be at increased health risk. However, BMI has limitations — it doesn't distinguish muscle from fat and doesn't account for where fat is stored. Your GP can assess your individual health beyond just BMI.
Can I use a weight calculator to check if I'm overweight?
Yes. Use our free BMI calculator above with your height and weight. If your BMI falls between 25 and 29.9, you're classified as overweight according to NHS guidelines. If it's 30 or above, you're in the obese category. Remember, BMI is just one health indicator. Your GP can give you personalised advice about what your weight means for your individual health.
What should I do if my weight calculator shows I'm in an unhealthy range?
First, remember that small changes make a difference. Even a 5–10% reduction in body weight can improve health markers like blood pressure and blood sugar. Consider speaking to your GP about NHS weight management services, which range from self-help programmes (tier 1) to specialist weight management services (tier 3). You can also use our free progress tracker to monitor gradual changes and celebrate small wins.
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.