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
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How to Calculate Your Weight Manually — UK Guide
Calculating your weight manually is straightforward once you understand the UK conversion formulas. Whether you need to convert between kilograms, stone, and pounds, or assess your weight against NHS health guidelines, knowing the maths behind these calculations helps you understand your health data better. This UK health guide walks you through the key formulas and provides practical context for what your weight means for your wellbeing.
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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.
a UK pharmacy Weight Conversion Formulas for UK Measurements
The UK uses a mix of metric (kilograms) and imperial (stone and pounds) measurements, so a UK pharmacy calculation between units is useful. Here are the key formulas:
- Kilograms to stone: Divide kg by 6.35029. Example: 70 kg ÷ 6.35 = 11.0 stone
- Kilograms to pounds: Multiply kg by 2.20462. Example: 70 kg × 2.20 = 154.3 lbs
- Stone to kilograms: Multiply stone by 6.35029. Example: 11 stone × 6.35 = 69.85 kg
- Stone and pounds to kg: (stone × 6.35) + (lbs × 0.454). This combines both imperial units into metric
These conversions are exact and match NHS health charts. Rounding to one decimal place is fine for most purposes. If a UK pharmacy calculation feels tedious, our free weight converter above handles these instantly across all UK measurements.
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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.
Using Your Manually Calculated Weight for Health Context
Once you have your weight in the unit you prefer, the next step is understanding what it means for your health. The NHS provides clear healthy weight ranges based on your height and BMI (body mass index). A healthy BMI sits between 18.5 and 24.9 for most UK adults — though South Asian, Chinese, Black African, and Black Caribbean adults have lower recommended thresholds at 18.5 to 22.9.
Use our free BMI calculator on this page to check where your manually calculated weight sits. If you're interested in weight management, our GLP-1 weight loss calculator can help project potential results if you're exploring treatment options with your GP. Your GP can also provide personalised nhs guidance on what your weight means for your individual health.
- 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's the easiest way to convert kg to stone without a calculator?
Divide kilograms by 6.35. For example, 80 kg ÷ 6.35 = 12.6 stone. If you need pounds too, take the decimal (0.6) and multiply by 14: 0.6 × 14 = 8.4 lbs, giving you 12 stone 8 lbs. Practising this a few times makes it automatic, though our weight converter above does this instantly for any weight.
Is manually calculating weight as accurate as using a calculator or app?
Yes, if you use the correct conversion formula. a UK pharmacy calculation using the formulas above (kg ÷ 6.35 for stone, kg × 2.20 for pounds) is mathematically identical to any app or calculator. The only difference is speed — a calculator saves time but doesn't improve accuracy. For health purposes, rounding to one decimal place is fine.
Why does the UK use both stone and kilograms for weight?
Historically, the UK used imperial measurements. Today, the NHS uses kilograms for clinical records and health guidelines, but many UK adults still think in stone from habit. This makes dual-unit understanding useful — your GP's records may show kg, but you might communicate your weight in stone to friends and family.
How do I know if my manually calculated weight is healthy?
Check your BMI using your height and weight. A healthy BMI is 18.5–24.9 according to NHS guidelines. Our free BMI calculator on this page does this instantly — simply enter your height and manually calculated weight, and you'll see your BMI and health category. Your GP can also review your personal weight in the context of your health history.
Can I manually calculate ideal weight ranges for my height?
Yes. Multiply your height in metres by itself, then multiply by 18.5 (lower healthy limit) and 24.9 (upper healthy limit). For example, at 1.73m: 1.73² = 2.99. Lower: 2.99 × 18.5 = 55.3 kg (8st 10lbs). Upper: 2.99 × 24.9 = 74.5 kg (11st 10lbs). Our BMI calculator calculates this for you automatically. ```
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.