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 Adults
Health calculators are simple, free tools that help you understand your weight and overall health status using NHS-aligned measurements. Whether you're checking your BMI, converting between stone and kilograms, or tracking weight loss progress, UK health calculators provide personalised insights based on your individual measurements. These tools are designed specifically for UK adults and use NHS guidance thresholds to give you context for your results.
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
Several UK health calculators can help you monitor your wellbeing and make informed decisions about weight management. The most widely used is the BMI calculator, which uses your height and weight to determine whether you fall into a healthy weight range according to NHS guidelines. Our free BMI calculator on this page instantly calculates your BMI and shows where you sit on the NHS scale — from underweight through to obese categories. Another essential tool is the weight converter, which translates between kilograms, stone, and pounds — crucial since UK adults typically use stone whilst NHS clinical systems use kilograms.
For those exploring weight management options, a GLP-1 weight loss calculator helps estimate potential results with prescription medications like Mounjaro or Wegovy, based on clinical trial data. A progress tracker allows you to log weekly weigh-ins and visualise your weight loss journey over time. Body composition calculators estimate body fat percentage, whilst waist-to-height ratio tools assess cardiovascular risk — all important for understanding health beyond simple weight numbers.
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.
Why Use NHS-Aligned Calculators?
Calculators based on NHS guidance give you reliable, evidence-based results rather than generic internet tools. The NHS uses specific BMI thresholds for different ethnic groups — for example, adults of South Asian, Chinese, Black African, or Black Caribbean heritage have lower healthy weight ranges due to higher health risks at standard BMI levels. UK health calculators account for these differences. They also reference healthy weight ranges specific to your height, helping you understand not just a single number but the context behind it.
Using an NHS-aligned calculator means your results are comparable to what your GP would assess during a health check. This makes it easier to have informed conversations with your healthcare provider about weight management, lifestyle changes, or whether prescription options might be appropriate for you.
- 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's the difference between a BMI calculator and a weight converter?
A BMI calculator uses your height and weight together to assess whether you're in a healthy weight range according to NHS guidelines. A weight converter simply translates between units (kg to stone, for example) without health assessment. Use our BMI calculator to understand your health status, and the weight converter when you need to switch between different measurement systems.
Are these calculators accurate for everyone?
Health calculators are screening tools, not diagnostic. They work well for most adults but have limitations — BMI doesn't distinguish muscle from fat, and calculators may be less accurate for elderly adults, athletes, or pregnant women. Always discuss results with your GP if you're concerned about your health or considering weight management treatment.
Can I use these calculators to track weight loss?
Yes. Our free progress tracker lets you log weekly weights and visualise trends over time. This is particularly useful if you're making lifestyle changes or considering GLP-1 medications like Mounjaro or Wegovy — tracking helps you see whether changes are working for you.
Do I need to see my GP before using a health calculator?
No, health calculators are free self-assessment tools anyone can use. However, if your results suggest overweight or obesity, or if you're considering weight loss medication, your GP can provide personalised advice and assess what options might be right for you.
What should I do if my BMI is outside the healthy range?
A BMI outside the healthy range doesn't mean you need to panic, but it's worth discussing with your GP. They can assess your overall health, family history, and any weight-related conditions. The NHS recommends sustainable weight loss of 0.5–1 kg per week through diet and activity changes — or prescription support if appropriate.
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.