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
Normal Body Weight Calculator for UK Adults
What counts as a "normal" or healthy body weight depends on your height, age, and individual health factors. In the UK, the NHS uses BMI (body mass index) as the primary screening tool to define healthy weight ranges. A normal body weight typically falls within a BMI of 18.5 to 24.9 for most adults, though ethnicity-adjusted thresholds apply to people of South Asian, Chinese, Black African, and Black Caribbean heritage. Rather than a single "ideal" weight, it's more helpful to think in terms of a healthy weight range for your height. Our free BMI calculator above will instantly show you whether your current weight falls within the NHS healthy weight range, and the weight converter helps you switch between kg, stone, and pounds.
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.
How UK Health Services Define Healthy Weight
The NHS defines healthy weight primarily through BMI categories, which divide adults into five groups: underweight (BMI below 18.5), healthy weight (18.5–24.9), overweight (25.0–29.9), obese (30.0–34.9), and severely obese (40.0+). However, BMI has important limitations — it doesn't distinguish between muscle and fat, and doesn't account for where fat is stored. NICE (National Institute for Health and Care Excellence) emphasises that waist circumference also matters: increased health risk begins at 94cm (37 inches) for men and 80cm (31.5 inches) for women. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — healthy weight begins at BMI 18.5–22.9 rather than 18.5–24.9, because these populations have higher cardiovascular and diabetes risk at the same BMI. Your GP can provide personalised guidance on what healthy weight means for your individual health profile, medical history, and goals.
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.
Calculating Your Healthy Weight Range
To find your healthy weight range, multiply your height in metres by itself, then multiply by 18.5 and 24.9 — this gives your lower and upper healthy weight bounds in kilograms. For example, at 1.73m (5ft 8in), healthy weight ranges from approximately 55kg (8st 10lbs) to 74kg (11st 9lbs). The weight converter on this page instantly switches between kg, stone, and pounds, so you can see your range in whichever measurement you prefer. Remember that this calculation assumes standard ethnicity thresholds — if you're of South Asian or Black African heritage, your healthy range may be slightly lower. Individual variation is huge; muscle mass, bone density, age, and medical conditions all affect where your healthy weight should be within or near the standard range. Rather than chasing a single number, focus on sustainable habits: regular physical activity, balanced nutrition, and monitoring how you feel.
- 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 ideal weight and healthy weight?
Ideal weight is theoretical — calculated from formulas like the Devine Formula. Healthy weight is practical and evidence-based, defined by BMI ranges and health outcomes. The NHS focuses on healthy weight ranges rather than single "ideal" numbers, because health depends on many factors beyond weight, including fitness, diet quality, and medical history.
Is BMI accurate for everyone?
BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat — athletes may have high BMI but low body fat. BMI also doesn't account for age, bone density, or where fat is stored. Your GP can assess whether BMI is appropriate for your individual circumstances and may recommend additional measurements like waist circumference.
Why do people of South Asian heritage have different healthy weight ranges?
Research shows that people of South Asian, Chinese, Black African, and Black Caribbean heritage have higher risk of type 2 diabetes, heart disease, and other health conditions at lower BMI levels than people of European heritage. The NHS therefore recommends lower BMI thresholds (18.5–22.9 rather than 18.5–24.9) to identify health risk earlier in these populations.
How much weight should I try to lose per week?
The NHS recommends losing 0.5–1kg (1–2 lbs) per week for sustainable, safe weight loss. This typically requires a calorie deficit of about 500 kcal per day. Faster weight loss may be possible under medical supervision but risks muscle loss and nutrient deficiencies. Your GP can advise on a safe rate for your circumstances.
Where can I get personalised advice about my healthy weight?
Your GP is your best first point of contact. They can assess your individual health, medical history, and any weight-related conditions, then advise on a realistic and healthy target weight for you. The NHS also offers free weight management support through tier 1 and 2 services, with specialist tier 3 services available in many areas for more intensive support.
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.