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
Online Health Calculators for UK Adults
Free online health calculators help UK adults understand their weight and health metrics using NHS guidelines. Whether you're checking your BMI, converting weight between stone and kilograms, or tracking progress towards a healthier weight, digital tools make health information accessible instantly. MyWeightCheck provides easy-to-use calculators aligned with NHS thresholds and UK measurements, helping you take the first step towards informed health decisions.
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.
What Health Calculators Are Available in the UK?
Online health calculators are digital tools designed to help UK adults assess key health metrics using NHS guidance. Common calculators include BMI calculators, which determine whether your weight falls within a healthy range according to NHS categories; weight converters, which translate between kilograms, stone, and pounds — essential for UK adults familiar with imperial measurements; and GLP-1 weight loss calculators, which estimate potential weight loss projections for adults considering prescription weight management options.
MyWeightCheck offers all these tools free of charge. Our BMI calculator instantly shows your health category against NHS thresholds, including ethnicity-adjusted guidance for South Asian, Chinese, Black African, and Black Caribbean adults. The weight converter handles complex conversions (like 75kg to stone and pounds) in seconds. For those exploring weight management options, our GLP-1 weight loss calculator provides realistic projections based on clinical trial data, helping you understand what to expect.
These calculators are complementary to, not replacements for, GP advice. Always consult your GP for personalised health guidance.
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.
Why Use NHS-Aligned Online Health Tools?
The NHS provides evidence-based health thresholds that form the foundation of reliable online calculators. Using tools aligned with UK health guidance ensures your results are clinically relevant and comparable to your GP's assessments. UK-specific calculators account for measurements you already use — stone and pounds — rather than forcing you to convert manually.
Online calculators offer three key advantages: they're immediate (results in seconds, not waiting for an appointment), private (check your health metrics in confidence), and accessible (available 24/7 from any device). For weight management, calculators help you track progress over time and understand whether your current approach is working. Many people use a free progress tracker to log weekly weight changes and see trends visually — this data is valuable to share with your GP when discussing next steps.
- 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.
Are online health calculators accurate?
Online calculators using NHS formulas are accurate for screening purposes. BMI calculators apply the same formula your GP uses. However, calculators provide general guidance only — they don't account for individual factors like muscle mass, medical conditions, or medications. Always discuss results with your GP for personalised interpretation.
What's the difference between kg and stone for weight?
Stone and pounds are traditional UK measurements; kilograms are metric and used internationally. 1 stone = 6.35kg; 1kg = 0.157 stone. A weight converter saves you doing the maths manually. Most NHS systems record weight in kg, but UK adults often think in stone, so having both units is useful.
Can an online calculator tell me if I'm overweight?
Yes. A BMI calculator compares your weight and height against NHS categories: underweight (BMI below 18.5), healthy weight (18.5–24.9), overweight (25–29.9), and obese (30+). For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds apply. Your result is a starting point — your GP can assess your individual health picture.
Should I use an online weight loss calculator before seeing my GP?
Yes. A GLP-1 weight loss calculator helps you understand realistic outcomes before consulting your GP about prescription weight management. Clinical trials show average weight loss of 15–21% depending on medication and individual factors. Calculators are educational tools — your GP will assess whether medication is suitable for you.
How often should I use a weight tracking calculator?
A progress tracker works best when updated weekly — the same day and time each week, ideally in the morning before eating. Tracking consistently (over 8+ weeks) helps you spot real trends rather than normal daily fluctuations. Share your tracking data with your GP when discussing weight management progress.
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.