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
How to Check Your Weight Using NHS Guidance
Checking your weight is an important first step in understanding your health. The NHS provides clear guidance on what constitutes a healthy weight for UK adults, based on BMI (body mass index) and other health markers. This guide explains how to assess your weight using NHS health advice, what your results mean, and when to speak with your GP about weight management.
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.
NHS Healthy Weight Ranges and BMI Categories
The NHS defines healthy weight using BMI — a measurement calculated from your height and weight. According to NHS guidance, a healthy BMI for most UK adults is between 18.5 and 24.9. You can calculate your personal BMI instantly using our free BMI calculator above to see which category you fall into.
- Underweight: BMI below 18.5
- Healthy weight: BMI 18.5–24.9
- Overweight: BMI 25.0–29.9
- Obese (Class I): BMI 30.0–34.9
- Obese (Class II): BMI 35.0–39.9
- Severely obese: BMI 40.0 and above
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — a healthy BMI starts at 18.5 but should aim for no higher than 22.9. This is because these groups face higher health risks at lower BMI levels. Your GP can discuss whether these adjusted thresholds apply to you.
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.
Checking Your Weight — Practical Steps and Tools
To check your weight using NHS health advice: First, weigh yourself on a reliable scale in the morning, without clothes, and record this weight. Then, measure your height in metres or centimetres. Use our free weight converter to ensure you have your measurements in the units you prefer — kg, stone, or pounds.
Next, calculate your BMI using these measurements (or use our BMI calculator above for gradual improvement). Compare your BMI to the NHS categories above. If your BMI falls outside the healthy range, or if you have concerns about weight-related health conditions like high blood pressure or type 2 diabetes, speak with your GP. They can discuss weight management strategies, lifestyle changes, or whether prescription support 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 is the NHS healthy weight range?
According to NHS guidance, a healthy BMI for most UK adults is 18.5–24.9. This translates to different weights depending on your height — for example, at 5ft 8in, healthy weight is approximately 55–75 kg (8st 10lbs to 11st 10lbs). Use our BMI calculator to find your personal healthy weight range.
How often should I check my weight?
The NHS recommends checking your weight regularly — typically once a week on the same day and time — to track trends rather than daily fluctuations. Weekly weigh-ins help you spot gradual changes. Track your progress over time using our free progress tracker to stay motivated and accountable.
Does BMI account for muscle mass?
No — BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat, so athletes or very muscular individuals may have a higher BMI but lower body fat. If you're concerned your BMI doesn't reflect your health accurately, discuss this with your GP or a healthcare professional.
What if my weight is above the healthy range?
If your BMI is above 24.9, speak with your GP. They can assess your overall health, discuss contributing factors, and recommend appropriate support — which might include lifestyle changes, dietary advice, NHS weight management services, or in some cases, prescription weight loss support.
Are there different healthy weight guidelines for South Asian adults?
Yes — the NHS recommends lower BMI thresholds for people of South Asian, Chinese, Black African, and Black Caribbean heritage. A healthy BMI for these groups should aim for 18.5–22.9 rather than 18.5–24.9. This reflects higher health risks at higher BMI levels in these populations. Discuss the most appropriate range for you with your GP.
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.