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 Weight Management
Health calculators are free digital tools that help you understand your weight, BMI, and progress towards a healthier lifestyle. Whether you're tracking your current weight status or planning weight management, these NHS-aligned calculators provide personalized insights based on your height, weight, and health goals. Using our free BMI calculator and weight converter, you can instantly see how your measurements fit into UK health guidance and identify where you stand on the healthy weight spectrum.
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.
Why UK Health Calculators Matter
Health calculators are evidence-based tools aligned with NHS guidance that help you assess your current health status quickly and accurately. Our free tools use your personal measurements to calculate your BMI (Body Mass Index), which is the primary screening tool used by the NHS to assess healthy weight ranges.
- BMI Calculator: Determines your BMI category (underweight, healthy weight, overweight, or obese) based on your height and weight in UK measurements (stone, pounds, and kilograms)
- Weight Converter: Instantly converts between kg, stone, and pounds — essential for understanding UK health advice which often uses different units
- Healthy Weight Range: Shows the target weight range for your height according to NHS thresholds
- Progress Tracking: Logs your weight over time so you can monitor sustainable progress towards your goals
These tools provide the baseline information your GP may use during health consultations and support informed decisions about weight management options.
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.
Using Calculators in Weight Management
Health calculators become even more valuable when combined with structured weight management approaches. If you're considering weight loss medication like GLP-1 injections, our GLP-1 weight loss calculator helps you understand potential outcomes alongside your current BMI baseline. Use your BMI calculation as your starting point, then track progress monthly using our progress tracker to see real changes over time.
Remember that individual results vary — calculators provide estimates and guidance, not assures. Your GP or a licensed prescriber can assess your personal health situation and recommend the most appropriate approach, whether that's lifestyle changes, prescription medication, or a combination of both.
- 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 a health calculator and how does it work?
A health calculator is a digital tool that uses your measurements (height, weight, age, sometimes gender) to calculate health metrics like BMI. Our free calculators use NHS-approved formulas to give you gradual improvement in UK measurements. They're designed to provide screening information, not medical diagnosis.
Why do UK adults need health calculators?
UK health guidance uses BMI as a key health screening tool, but BMI itself can be confusing to calculate manually. Calculators remove the maths and instantly show you where you stand on the healthy weight spectrum according to NHS thresholds, making it easier to understand your health status.
Are health calculators accurate?
BMI calculators are accurate for their intended purpose as a population-level screening tool. However, BMI has limitations — it doesn't distinguish muscle from fat. Our calculator tools also note these limitations and recommend consulting your GP for personalized health advice.
Can I use a calculator to decide if I need weight loss medication?
Calculators provide useful baseline information, but medication eligibility requires a clinical assessment by a GP or licensed prescriber. They'll consider your BMI, health conditions, and personal circumstances. Our GLP-1 calculator can show potential outcomes, but prescribing decisions are made by healthcare professionals.
How often should I use a health calculator to track progress?
Monthly weigh-ins are typically recommended for sustainable weight management — more frequent checking can be demotivating. Use our progress tracker to log monthly measurements and visualize trends over 3–6 months, which is a realistic timeframe to see meaningful changes.
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.