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 Much Weight Can I Lose Calculator — Find Your Ideal Weight
The amount of weight you should aim to lose depends on your current weight, height, and personal health goals. Our free BMI calculator on this page helps you determine your ideal weight and healthy weight range based on NHS guidelines. Understanding your personal numbers is the first step towards sustainable weight loss. This guide explains how to interpret your results and create a realistic weight loss plan tailored to your body and circumstances.
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.
What Your BMI Calculator Results Mean
Your BMI (Body Mass Index) shows whether your weight falls into a healthy range for your height. The BMI calculator on this page instantly shows your personal BMI and how it compares to NHS healthy weight guidelines.
- Healthy weight range: BMI 18.5–24.9 for most UK adults (lower thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage)
- Overweight range: BMI 25.0–29.9 — losing 5–10% of body weight can have significant health benefits
- Obese range: BMI 30.0 and above — weight loss is strongly recommended to reduce health risks
Once you know your current BMI, calculate your healthy weight range for your height using the calculator. This shows you the kg and stone weight range NHS considers healthy for your measurements. The difference between your current weight and the upper limit of your healthy range tells you approximately how much weight loss could move you into a healthier category.
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.
Creating a Realistic Weight Loss Plan
The NHS recommends losing 0.5 to 1 kg (1–2 lbs) per week for sustainable results. This means if you need to lose 10 kg to reach your healthy weight range, a realistic timeframe is 10–20 weeks (roughly 2.5–5 months). Faster weight loss is possible with medical support such as prescription weight loss medication, but sustainable loss happens alongside dietary changes and increased physical activity.
Once you know your target, track your progress using our free progress tracker. You can also use our GLP-1 weight loss calculator if you're considering prescription weight loss treatment like Mounjaro or Wegovy — this shows estimated weight loss timelines at different doses, helping you understand how medication might support your goals.
- 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 do I know if I need to lose weight?
Use the free BMI calculator on this page to see your current BMI and healthy weight range for your height. If your BMI is above 25, the NHS considers you overweight. Even modest weight loss of 5–10% can improve health markers like blood pressure and blood sugar. Speak to your GP if you're unsure whether weight loss is right for you.
What's a realistic amount of weight to lose?
The NHS recommends losing 0.5–1 kg per week for sustainable results. This means losing 10 kg could realistically take 10–20 weeks. Faster loss is possible with medical support, but slower loss is more likely to be maintained long-term and helps preserve muscle mass.
What if my BMI is in the healthy range but I want to lose more weight?
If you're already in a healthy weight range (BMI 18.5–24.9), further weight loss may not be necessary for health reasons. Speak to your GP before pursuing additional weight loss. Focus instead on maintaining your healthy weight through balanced nutrition and regular physical activity.
Can weight loss calculators predict exactly how much I'll lose?
No calculator can predict your individual weight loss — results vary based on your diet, activity level, metabolism, medical conditions, and genetics. Use our calculator as a guide for realistic targets, not as a assures. A GP or dietitian can give more personalised projections.
Should I consider weight loss medication or GLP-1 injections?
Weight loss medication like Mounjaro or Wegovy is available on prescription in the UK if you meet eligibility criteria (BMI 30+ or 27+ with health conditions). Our GLP-1 weight loss calculator can show estimated results. Any medication decision requires a clinical assessment from a prescriber — it's not suitable for everyone.
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.