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 Adults
Health calculators are simple tools that help you understand your weight, BMI, and progress towards a healthier lifestyle. At MyWeightCheck, we provide free, easy-to-use calculators aligned with NHS guidance to help you make informed decisions about your health. Whether you're tracking your current weight in stone and pounds, calculating your BMI, or planning weight loss, our calculators give you instant, personalised results based on your own measurements. No registration needed — just enter your details and get clear health insights in seconds.
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 Do and How They Work
Health calculators are digital tools that process your personal measurements and instantly return health-related information. At MyWeightCheck, our BMI calculator uses your height and weight to calculate your Body Mass Index against NHS thresholds, showing whether you fall into the healthy weight, overweight, or obese categories.
Our weight converter instantly translates between kilograms, stone, and pounds — essential for UK health contexts where stone is the common measurement but NHS clinical records use kilograms. Our GLP-1 weight loss calculator estimates potential weight loss outcomes based on current weight and medication type, helping you understand realistic expectations. Our progress tracker logs weekly weigh-ins and shows your journey over time.
All calculators follow NHS guidelines and UK health standards, including ethnicity-adjusted BMI thresholds for South Asian, Black African, and Caribbean populations who face higher cardiovascular risk at lower BMI levels.
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.
Who Should Use Health Calculators and How to Access Them
Health calculators are useful for anyone interested in understanding their current health status or tracking weight management progress. They're particularly helpful if you're considering weight loss, starting a fitness programme, or monitoring health following a medical consultation. Our free calculators require no registration, no app download, and no subscription — they're available instantly on MyWeightCheck.
Simply enter your height, current weight, and age where required, and the calculator processes your information locally on your device. Results appear immediately with NHS-aligned guidance. If you're exploring prescription weight loss options, our GLP-1 calculator can help you understand eligibility and potential outcomes, though a full clinical assessment from your GP or a licensed prescriber is always required for actual treatment. Start with any calculator that matches your current question.
- 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 MyWeightCheck calculators accurate?
Yes. Our calculators use clinically-established formulas aligned with NHS guidelines. BMI uses the standard formula: weight (kg) ÷ height (m)². Results are mathematically accurate based on your inputs. However, BMI has limitations — it doesn't distinguish muscle from fat, and individual health status varies. Always discuss results with your GP for personalised interpretation.
Do I need to create an account to use the calculators?
No. All MyWeightCheck calculators are completely free and require no registration, login, or email address. Simply visit the tool, enter your measurements, and get instant results. Your data is not stored — all calculations happen on your device.
How often should I use the weight tracker?
Weekly weigh-ins are ideal for tracking progress without becoming obsessive about daily fluctuations (which vary with hydration, meals, and hormones). Our progress tracker stores your history and shows trends over time. If you're using prescription weight loss medication, weekly tracking helps you and your prescriber monitor progress at check-in appointments.
Can calculators tell me if I need weight loss medication?
Calculators can show your BMI and eligibility criteria, but they cannot provide medical advice. Only a GP or licensed prescriber can assess whether prescription weight management is appropriate for you, considering your full health history, medications, and individual circumstances. Use our calculator as an informational starting point, then discuss results with your healthcare professional.
What's the difference between MyWeightCheck calculators and commercial weight loss apps?
MyWeightCheck provides free, independent UK health information tools with no commercial agenda — we don't sell products or medications. Our calculators are educational, not promotional. We reference NHS guidance openly and highlight calculator limitations. Unlike some apps, we don't use gamification to drive daily engagement or sell premium features.
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.