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 Percentage Calculator — Measure Progress Beyond Kilograms
A weight percentage calculator helps you measure weight loss as a percentage of your starting body weight, giving you a clearer picture of real progress. This is particularly useful in healthy weight management because losing 5kg means something very different for a person weighing 80kg versus 120kg. By calculating the percentage, you can track meaningful health improvements and understand how your weight loss journey aligns with NHS guidance and evidence-based health outcomes.
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.
Why Weight Percentage Matters More Than Scale Weight
The NHS recognises that percentage weight loss is a more meaningful health indicator than absolute kilograms alone. Research shows that losing just 5% of body weight can significantly improve blood pressure, blood sugar control, and reduce joint strain. Losing 10% typically brings measurable improvements in cholesterol levels and sleep quality.
- A 10kg loss sounds substantial, but it represents different achievements: 10kg is 12.5% of an 80kg person's weight, but only 8.3% of a 120kg person's weight
- The same percentage loss produces similar health improvements across different starting weights
- Tracking percentage helps you celebrate real progress, especially important during weight management programmes that may include lifestyle changes, increased physical activity, or prescription medication
- Our free BMI calculator and weight converter above can help you monitor your starting point and track changes over time
This is why many health professionals recommend focusing on the first 5–10% loss as an initial achievable goal, rather than aiming for an "ideal" weight immediately.
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 Calculate Your Weight Loss Percentage
The formula is straightforward: (Starting weight − Current weight) ÷ Starting weight × 100 = Percentage loss. For example, if you started at 100kg and now weigh 95kg, your calculation is (100 − 95) ÷ 100 × 100 = clinically studied weight loss.
Use our free progress tracker above to log your weight regularly and automatically calculate your percentage loss over weeks and months. This removes the maths and lets you focus on the health journey itself. Many people find that tracking percentage alongside BMI gives the fullest picture of health progress, especially when weight management involves multiple factors like diet, exercise, or medical support.
- 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 percentage of weight loss is considered healthy?
The NHS recommends losing 0.5–1kg per week, which typically equates to 1–2% of body weight per week for sustainable, healthy loss. Even 5% total loss brings measurable health benefits like improved blood pressure and better blood sugar control.
Is percentage weight loss better than BMI for tracking progress?
Both are useful. Percentage loss shows your personal progress relative to your starting weight, while BMI helps you understand how your weight compares to healthy ranges for your height. Using our free BMI calculator alongside percentage tracking gives you the fullest health picture.
How often should I recalculate my weight loss percentage?
Weekly weigh-ins are typical, though some people prefer fortnightly or monthly measurements to avoid daily fluctuations. Daily weight naturally varies due to water retention, food intake, and hormones—tracking percentage over longer periods smooths these variations out.
Does weight percentage apply if I'm taking Mounjaro or Wegovy?
Yes. Clinical trials of weight management injections like Mounjaro and Wegovy measure success as percentage body weight lost—typically 15–21% over 72 weeks for Mounjaro and around 15% for Wegovy. Calculating your own percentage helps you track actual progress against clinical data.
Can I use the weight converter and BMI calculator to set a weight loss goal?
Absolutely. Use our free weight converter to understand your current weight in different units (kg, stone, lbs), then use the BMI calculator to see what weight range would put you in a healthy BMI for your height. Your GP or a healthcare professional can help you set a realistic, personalised goal based on your health.
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.