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
BMI Tracker NHS — How to Monitor Your Health
A BMI tracker helps you monitor your weight health using NHS-approved guidelines. BMI (body mass index) is a simple screening tool that estimates whether your weight falls into a healthy range for your height. By tracking your BMI regularly, you can spot trends and make informed decisions about your health. Our free BMI calculator makes it easy to check your current BMI instantly and understand where you sit on the NHS bmi range. This guide explains how to use BMI tracking effectively and what the NHS categories mean for you.
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.
Understanding the NHS BMI Formula and Categories
The bmi formula is straightforward: your weight in kilograms divided by your height in metres squared (kg ÷ m²). The NHS uses standardised bmi categories uk to help interpret your result:
- Below 18.5: Underweight
- 18.5 to 24.9: Healthy weight (this is your target healthy bmi range)
- 25.0 to 29.9: Overweight
- 30.0 to 34.9: Obese (Class I)
- 35.0 to 39.9: Obese (Class II)
- 40.0 and above: Severely obese (Class III)
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the overweight bmi threshold is lower. A healthy BMI for these groups starts at 18.5 and goes up to 22.9, with overweight beginning at 23.0. This adjustment exists because these populations face higher health risks from excess weight at lower BMI levels. Tracking your BMI against the correct category for your ethnicity is important for accurate health assessment.
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.
BMI Limitations and Why Tracking Alone Isn't Enough
While bmi limitations are important to understand, tracking your nhs bmi is still valuable. BMI does not distinguish between muscle and fat—a very muscular person may have a high BMI but low body fat. BMI also doesn't account for where fat is stored on your body; waist circumference matters too. For this reason, the NHS recommends measuring your waist as well: over 94 cm (37 inches) for men or 80 cm (31.5 inches) for women indicates increased health risk.
Use our BMI calculator above alongside the weight converter to track changes in both kilograms and stone. For sustained weight management, consider our GLP-1 weight loss calculator if you're exploring medical options, or track your progress over time with our free progress tracker to see the bigger picture of your health journey.
- 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.
How often should I track my BMI?
The NHS suggests checking your BMI every 1–3 months if you're actively managing your weight, or annually as part of routine health checks. Tracking too frequently (weekly) can be frustrating because BMI changes are gradual. Use our free BMI calculator to check your progress monthly for a realistic picture of change.
What if my BMI is in the healthy range but I feel unhealthy?
BMI is just one health marker. Your GP can assess other factors including blood pressure, cholesterol, blood sugar, fitness level, and family history. Discuss your concerns with your GP, who may recommend additional health checks beyond BMI alone.
Is BMI different for children?
Yes—children's BMI uses age and sex-specific centile charts, not adult categories. If you're concerned about a child's weight, contact your GP or health visitor, who can assess using the correct UK90 growth reference charts rather than adult BMI ranges.
Can BMI tracker apps replace seeing my GP?
No. Tracking tools are helpful for monitoring trends, but only a GP can provide personalised health advice based on your complete medical picture. If you're concerned about your weight or health, always discuss this with your GP for a proper assessment.
Why is waist measurement important alongside BMI?
Waist measurement indicates where fat is stored, which matters for health risk. Even with a healthy BMI, excess belly fat increases risk of heart disease and diabetes. The NHS recommends measuring waist circumference alongside BMI for a fuller health picture.
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.