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
Weight Calculator Guide for UK Adults
A weight calculator is an essential tool for understanding your health in UK measurements. Whether you need to convert between kilograms, stone, and pounds, calculate your BMI, or track your weight management progress, having the right tools makes it simple. MyWeightCheck provides free, NHS-aligned calculators to help you stay informed about your weight and overall wellbeing. This guide explains what weight calculators do, how to use them effectively, and how they fit into your broader health management plan.
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 Weight Calculators Available
Several types of weight calculators serve different purposes in your health management:
- Weight converters instantly convert between kilograms, stone, and pounds — essential because UK adults commonly use stone and pounds, whilst NHS clinical records use kilograms.
- BMI calculators determine your Body Mass Index using your weight and height, helping you understand where you fall within NHS healthy weight guidelines (18.5–24.9 for most adults).
- Healthy weight range calculators show what weight range is appropriate for your specific height according to NHS thresholds.
- GLP-1 weight loss calculators project potential weight loss with medications like Mounjaro or Wegovy, based on clinical trial data — useful if you're exploring prescription weight management options with your GP.
- Progress trackers log your weight over time, helping you visualise trends and stay motivated during weight management journeys.
Each serves a distinct purpose in weight management and health monitoring.
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 to Use a Weight Calculator Effectively
Using a weight calculator correctly ensures you get accurate, useful information. For weight converters, simply enter your weight in one unit (e.g. kilograms) and the calculator instantly shows the equivalent in stone and pounds — helpful for understanding NHS records or comparing with friends who use different measurements.
For BMI calculators, you'll need your weight and height. The calculator compares your result against NHS guidance: a healthy BMI is 18.5–24.9 for most adults, though lower thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage.
Remember: BMI is a useful screening tool but doesn't account for muscle mass or where fat is stored. Your GP can provide personalised nhs health advice about what your results mean for your individual situation.
- 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 weight converter and a BMI calculator?
A weight converter changes weight between units (kg to stone/pounds) — purely mathematical. A BMI calculator uses both weight and height to determine your Body Mass Index and compare it against NHS healthy weight guidelines. They serve different purposes in your health management.
Is BMI accurate for everyone?
BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat, so athletes may have a high BMI but low body fat. It also doesn't account for age, genetics, or where fat is stored on your body. Your GP can assess your individual health context.
How often should I use a weight calculator to track progress?
Weekly weigh-ins are typical for weight tracking, though some people prefer fortnightly or monthly checks to avoid fixating on daily fluctuations. Use a progress tracker to log consistently and spot trends. The NHS recommends weight loss of 0.5–1kg per week for sustainable results.
Can weight calculators tell me if I need weight loss medication?
No. Weight calculators provide informational data (BMI, conversions, projections), but only a GP or licensed prescriber can assess whether you're eligible for prescription weight loss treatment like Mounjaro or Wegovy. Eligibility depends on BMI, health conditions, and individual assessment.
What if my weight calculator shows I'm overweight according to NHS guidelines?
NHS guidance recommends discussing results with your GP, especially if you have weight-related health conditions like diabetes or high blood pressure. Your GP may suggest lifestyle changes, refer you to weight management services, or discuss prescription options if appropriate for you.
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.