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
Free Health Calculators for UK Weight Management
MyWeightCheck provides a range of free, evidence-based health calculators designed specifically for UK adults. Whether you need to check your BMI, convert between stone and kilograms, estimate weight loss with GLP-1 medication, or track your progress over time, our tools are built to NHS standards and UK measurements. Each calculator is straightforward to use and gives you gradual improvement to help you understand your health and make informed decisions alongside guidance from your GP.
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 Calculators Are Available on MyWeightCheck?
MyWeightCheck offers four core free health calculators designed for UK adults:
- BMI Calculator — Calculate your body mass index using your height and weight. Results are aligned with NHS BMI categories and include ethnicity-adjusted thresholds for South Asian, Chinese, Black African, and Black Caribbean users.
- Weight Converter — Instantly convert between kilograms, stone, and pounds. Essential for understanding weight in both metric and imperial formats.
- GLP-1 Weight Loss Calculator — Estimate potential weight loss outcomes with prescription GLP-1 medications like Mounjaro (tirzepatide) or Wegovy (semaglutide), based on clinical trial data.
- Progress Tracker — Log your weight over time and visualise your progress with simple, private tracking tools.
All tools are free to use, require no registration, and respect your privacy.
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 These Calculators for UK Health Guidance?
These calculators provide evidence-based, actionable information aligned with NHS health standards. They help you understand your current health metrics and make informed conversations with your GP. The BMI calculator uses NHS thresholds; the weight converter accounts for UK preferences for stone and pounds; the GLP-1 calculator reflects real clinical trial data from STEP and SURMOUNT studies; and the progress tracker supports sustainable, long-term weight management alongside diet and physical activity.
Each tool is designed to be simple, fast, and free — no hidden costs, no registration needed, and no data collection.
- 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.
Do I need to create an account to use MyWeightCheck calculators?
No. All MyWeightCheck calculators are completely free and require no account or registration. Simply visit the page, enter your information, and get gradual improvement. Your data is not stored or tracked.
Are these calculators suitable for children?
The BMI calculator uses adult NHS categories. For children under 18, BMI assessment requires age and sex-specific growth reference charts. Always consult your GP or the NHS Healthy Weight Calculator for children's BMI assessment.
Which calculator should I use first?
Start with the BMI calculator to understand your current health category using NHS standards. Then use the weight converter if you need to switch between metric and imperial units. If you're exploring GLP-1 medication, try the weight loss calculator alongside your GP's assessment.
Can I share my calculator results with my GP?
Yes. Take a screenshot of your results and bring them to your GP appointment. Calculators provide helpful baseline information for discussing weight management and health options with your healthcare professional.
Are the calculators based on UK guidance?
Yes. All calculators are aligned with NHS guidelines, NICE recommendations, and UK health standards. Measurements use UK units (stone, pounds, kilograms, centimetres), and ethnicity-adjusted thresholds reflect NHS best practice.
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.