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 — Your Essential UK Wellness Tools
Health calculators are practical, free tools that help you understand your weight, BMI, and potential health outcomes. Whether you're tracking your current health status or exploring weight management options, having access to reliable UK health information and calculators makes informed decision-making easier. MyWeightCheck provides several free calculators aligned with NHS guidance to help you take control of your health journey. These tools are designed specifically for UK measurements and health thresholds, so you get accurate, relevant information for your situation.
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 on MyWeightCheck?
MyWeightCheck offers four essential free health calculators designed to support your UK health guide and wellness goals:
- BMI Calculator — Calculate your Body Mass Index instantly using your height and weight. Get your personal BMI result and see where you fall on the NHS healthy weight scale.
- Weight Converter — Convert between kg, stone, and pounds instantly. Perfect for understanding your weight in the format you're most comfortable with.
- GLP-1 Weight Loss Calculator — If you're considering weight management medication like Mounjaro or Wegovy, this tool projects potential weight loss outcomes based on clinical trial data.
- Progress Tracker — Log your weight over time and visualise your progress with a simple, free tracking tool. Monitoring your journey helps maintain motivation and accountability.
All calculators are aligned with NHS guidance and use current UK health thresholds. No registration required — just use them whenever you need them.
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 for Weight Management
Start by calculating your current BMI using our free calculator to understand your baseline health status according to NHS categories. Then, if you're interested in weight management, use the weight converter to track your weight in your preferred units — many UK adults use stone and pounds, so having both options available is helpful.
For those exploring prescription weight loss medication, our GLP-1 calculator can estimate potential weight loss based on doses of medications like Mounjaro or Wegovy. Remember that individual results vary significantly. Finally, use the progress tracker to log weekly or monthly weights and see your progress visualised over time. This builds accountability and helps you stay motivated on your weight management journey.
- 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 these health calculators accurate?
Yes. Our BMI calculator uses the standard NHS formula and aligns with official UK health thresholds. The weight converter uses exact conversion values. The GLP-1 calculator is based on STEP and SURMOUNT clinical trial data. However, all tools are for informational purposes — your GP can provide personalised medical advice.
Do I need to pay for these calculators?
No. All MyWeightCheck calculators are completely free. There's no registration, no subscription, and no hidden costs. We provide these tools as part of our free UK health information service to help you make informed health decisions.
What does my BMI result mean?
Your BMI falls into NHS categories: healthy weight (18.5–24.9), overweight (25–29.9), or obese (30+). For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds apply. BMI is a useful screening tool but has limitations — it doesn't account for muscle mass.
Can the weight loss calculator predict my exact weight loss?
No. The GLP-1 weight loss calculator shows average results from clinical trials — your individual results may differ significantly. Weight loss depends on many factors including diet, exercise, metabolism, and individual response to medication. Always discuss realistic expectations with your prescriber.
How often should I use the progress tracker?
Weekly weigh-ins are typical for weight management. Weigh yourself on the same day and time for consistency. Weight fluctuates daily due to water retention and digestion, so weekly tracking smooths out natural variations and shows true progress more clearly.
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.