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
What Are the Tools on MyWeightCheck?
MyWeightCheck provides four free health calculators and tracking tools designed to help you understand and manage your weight. These tools offer NHS-aligned guidance, work with UK measurements (stone, lbs, and kg), and require no registration. Whether you're checking your BMI, converting between weight units, exploring weight loss options, or tracking progress over time, each tool is built to support informed health decisions alongside advice 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.
The Four Free Tools Available on MyWeightCheck
1. BMI Calculator — Enter your weight and height to calculate your Body Mass Index instantly. The calculator shows where your BMI falls according to NHS guidelines (healthy weight, overweight, obese categories) and includes ethnicity-adjusted thresholds for South Asian, Chinese, Black African, and Black Caribbean adults. This is helpful because these groups face higher health risks at lower BMI levels.
2. Weight Converter — Convert between kilograms, stone, and pounds in seconds. The weight converter handles all combinations: kg to stone, kg to lbs, stone to lbs, and stone-and-pounds format. UK adults often need to switch between units for health appointments, online health information, or fitness tracking, so this tool removes the maths.
3. GLP-1 Weight Loss Calculator — If you're considering prescription weight loss medications like Mounjaro or Wegovy, this calculator helps you estimate potential weight loss based on clinical trial data. Enter your current weight and the medication dose, and it projects a realistic weight loss range. Results vary between individuals, but this gives context for conversations with your GP or prescriber.
4. Progress Tracker — Log your weight over time and visualise your progress on a simple chart. The tracker stores up to 12 months of data (in your browser, not on our servers) so you can see trends and celebrate milestones without manually writing figures down.
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 the Tools Support UK Health Guidance
All MyWeightCheck tools are built around NHS health standards and UK measurements. The BMI calculator references NHS weight categories. The weight converter uses exact metric-to-imperial conversions. The GLP-1 calculator draws from SURMOUNT and STEP clinical trial data, clearly stating that individual results vary and that medication is only one part of weight management alongside diet and physical activity. The progress tracker has no hidden costs, no app download, and no data sharing — it's private and straightforward. Use any combination of these tools to get a fuller picture of your health: calculate BMI, convert your weight for context, explore what evidence-based weight loss options might suit you, and track changes over weeks and months.
- 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 or log in to use these tools?
No. All four tools are completely free and require no registration, login, or personal data entry beyond the health measurements you choose to enter (weight, height, current dose if using the GLP-1 calculator). Your data is not stored on our servers.
Is the GLP-1 Weight Loss Calculator the same as a prescription?
No. The calculator shows estimated weight loss based on clinical trial data — it is informational only. It does not replace a clinical assessment from your GP or a licensed prescriber. Mounjaro and Wegovy are prescription-only medicines, and eligibility depends on your individual health.
Which tool should I use first?
Start with the BMI calculator to understand your current weight category according to NHS guidelines. Then use the weight converter if you need to see your weight in different units. If you're interested in weight loss medication, try the GLP-1 calculator next. The progress tracker is useful once you've started making changes and want to monitor outcomes.
Can the progress tracker send me reminders to log my weight?
The progress tracker is a simple logging tool — it does not send notifications or reminders. You can log your weight whenever you choose, as often as you like, using the date fields provided on the page.
Are these tools suitable for children or teenagers?
The BMI calculator is not suitable for children under 18 — children use age and sex-specific centile charts, not adult BMI categories. Please direct children and teenagers to NHS resources or speak to your GP for age-appropriate guidance.
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.