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 essential tools for understanding your weight and wellbeing in the UK context. Whether you need to convert between stone and kilograms, calculate your BMI using NHS guidelines, or estimate potential weight loss outcomes, the right calculator empowers you to make informed health decisions. MyWeightCheck provides a suite of free, evidence-based health calculators aligned with NHS guidance to support your personal health goals.
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.
Types of UK Health Calculators Available
Several key health calculators help UK adults monitor their wellness. Our BMI calculator uses your height and weight to determine your body mass index against NHS categories—essential for understanding whether your weight falls into the healthy, overweight, or obese ranges. For those using different measurement units, our weight converter instantly converts between kilograms, stone, and pounds, making it easy to compare your weight across different systems.
- BMI Calculator: Assess your weight category using NHS thresholds for all adults and ethnicity-adjusted guidance for South Asian, Chinese, Black African, and Black Caribbean populations
- Weight Converter: Switch seamlessly between kg, stone, and lbs—essential for understanding UK health advice and comparing international guidelines
- GLP-1 Weight Loss Calculator: If you're exploring prescription weight management options like Mounjaro or Wegovy, this calculator helps estimate potential outcomes based on clinical trial data
Each calculator provides context about what your results mean for your health according to current NHS guidance.
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 Health Calculators Alongside Professional Advice
While calculators provide valuable insights, they work best as part of a broader health picture. BMI, for example, is a useful screening tool but doesn't account for muscle mass, bone density, or where fat is stored on your body. If you're considering prescription weight loss medication, a health calculator can help you understand eligibility and potential outcomes—but your GP or a licensed prescriber must assess whether treatment is appropriate for you individually.
Use these free tools to track your progress, understand your health context, and prepare informed conversations with your healthcare team. Our progress tracker lets you log your weight journey over time, while our calculators provide the baseline measurements and context you need to set realistic, evidence-based health goals.
- 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 the difference between BMI and body composition?
BMI (body mass index) is a screening measurement based on height and weight only. It doesn't distinguish between muscle and fat. Body composition analysis measures the percentage of your body that is fat, muscle, bone, and water. BMI is useful for population-level health screening, but body composition gives a more detailed picture. Your GP can discuss which measurement is most relevant for your health.
Why do UK health calculators use stone and kilograms?
The UK uses a mix of measurement systems. Stone and pounds are traditional in the UK for personal body weight, whilst NHS clinical records typically use kilograms. Our weight converter lets you work in whichever unit you're comfortable with, then translates to NHS measurements. This is important because NHS guidance (like BMI thresholds and medication eligibility) is expressed in kilograms.
Can health calculators help me decide if I'm eligible for weight loss injections?
Health calculators can show whether your BMI might fall within typical eligibility ranges for medications like Mounjaro or Wegovy—usually BMI 30 or above, or 27–29.9 with weight-related health conditions. However, only a UK-licensed prescriber can assess your full health picture and confirm eligibility. Use our GLP-1 calculator to understand potential outcomes, then speak with your GP about whether prescription treatment is suitable for you.
How often should I use a health calculator to track progress?
Weekly weigh-ins and BMI recalculations are common, though daily weighing can be emotionally challenging for some. Many people find monthly calculator checks more sustainable. Our progress tracker lets you log weekly or monthly measurements and see trends over time. Sustainable weight loss is typically 0.5–1 kg per week, so allow several weeks before expecting significant calculator changes.
Are ethnicity-adjusted BMI thresholds available in UK health calculators?
Yes—the NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean heritage because these groups face higher health risks at lower BMI levels. Our BMI calculator includes ethnicity-adjusted guidance so you get thresholds relevant to your individual health profile, consistent with current NHS recommendations.
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.