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 Calculators for UK Adults — BMI, Weight & Fitness
Health calculators are simple tools that help you understand your weight, fitness level, and overall health status using evidence-based measurements. Whether you're tracking your BMI, converting between stone and kilograms, or monitoring your weight loss progress, these free UK health calculators provide gradual improvement aligned with NHS guidance. Understanding your health metrics is the first step towards making informed decisions about 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.
Types of Health Calculators Available
Several key calculators help you assess your current health and set realistic goals:
- BMI Calculator — Calculates your Body Mass Index to see if your weight falls within the healthy range according to NHS guidelines. Enter your height and weight, and get your BMI category instantly.
- Weight Converter — Converts your weight between kilograms, stone, and pounds. Essential for UK adults who use stone in everyday life but need to understand medical measurements in kg.
- GLP-1 Weight Loss Calculator — If you're considering prescription weight loss medication, this tool estimates potential weight loss based on clinical trial data. Results vary by individual.
- Progress Tracker — Log your weight over time to visualize your progress and stay motivated throughout your weight management journey.
Each calculator uses verified formulas and NHS-aligned thresholds to give you accurate information.
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.
How to Use Health Calculators Effectively
For best results, use these calculators as part of a broader approach to health. Take accurate measurements — weigh yourself at the same time each day, ideally in the morning before eating. Check your results regularly but remember that weight fluctuates daily due to hydration, hormones, and food intake.
Use the BMI calculator to understand if your current weight falls within the healthy range for your height. If you're overweight or obese according to NHS categories, speak with your GP about safe weight management options. For those considering medication like Mounjaro or Wegovy, the GLP-1 weight loss calculator can show projected outcomes based on clinical trial averages — though individual results always vary significantly.
- 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 the difference between BMI and body fat percentage?
BMI measures weight relative to height and gives a screening category (healthy, overweight, obese). Body fat percentage measures the actual proportion of fat in your body. BMI doesn't distinguish between muscle and fat, so athletes may have high BMI but low body fat. Both metrics are useful — BMI for population health screening, body fat for detailed composition analysis.
Why do UK health calculators use different units (stone, kg, pounds)?
UK adults traditionally use stone and pounds for body weight, but NHS clinical measurements use kilograms. Calculators offer all three units because GPs discuss weight in kg, but you probably think about your weight in stone. Our weight converter helps you switch between units instantly.
Can I trust health calculator results without seeing my GP?
Health calculators provide educational information based on evidence-based formulas and NHS thresholds. However, they're screening tools, not diagnostic. If your BMI suggests you're overweight or obese, or if you have health concerns, always discuss results with your GP. They can assess your individual circumstances, medications, and family history.
How often should I use the progress tracker?
Weigh yourself once per week at the same time and day — daily weighing can be demotivating due to natural fluctuations. Log your weight in the progress tracker weekly to spot trends over weeks and months. A gradual downward trend is healthier than rapid drops, and the NHS recommends losing 0.5–1 kg per week.
Are these calculators suitable for children?
BMI calculators for children must use different age and sex-specific charts — adult BMI categories don't apply to children. Use the NHS Healthy Weight Calculator for children instead. For teens or young adults unsure about their weight, always discuss with your GP or school health service first.
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.