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
What Is a Stone in Weight?
A stone is a unit of weight used primarily in the UK, Ireland, and a few Commonwealth countries. One stone equals exactly 14 pounds or approximately 6.35 kilograms. In the UK, body weight is traditionally measured in stone and pounds, which is why you'll see weights expressed as "11 stone 7 pounds" rather than a single kilogram figure. Understanding stone is essential for UK health guidance, NHS measurements, and using weight management tools effectively.
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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.
The Stone and Pounds System Explained
A stone (st) is a traditional British unit of mass that has been used for centuries. The exact conversion is:
- 1 stone = 14 pounds (lbs) exactly
- 1 stone = 6.35029 kilograms (kg)
- 1 kilogram = 0.157473 stone
Most UK adults naturally express their weight in stone and pounds — for example, "I weigh 12 stone 3 pounds" — rather than using kilograms alone. This reflects how weight management, healthy weight ranges, and body weight discussions are traditionally framed in British culture. Your GP may use kilograms in clinical notes, but conversations about weight often revert to stone. The NHS provides healthy weight ranges in both metric and imperial measurements to accommodate this preference.
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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.
Converting Between Stone, Pounds, and Kilograms
Converting between units is straightforward once you know the key relationships. To convert kg to stone, divide by 6.35029. To convert stone to kg, multiply by 6.35029. Our free weight converter above handles these calculations instantly — just enter your weight and switch between units. For BMI calculations and health context, you can use our BMI calculator which accepts weight in stone, pounds, or kilograms. Whether you're tracking weight loss, checking your healthy weight range, or managing weight with lifestyle changes or medication, having flexibility with these units makes UK health guidance much more accessible and practical.
- 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.
Why does the UK use stone instead of kilograms?
Stone is a traditional unit with deep historical roots in British culture and commerce. While the metric system (kilograms) is used in clinical settings and by healthcare professionals, stone and pounds remain the colloquial standard for everyday weight discussions among UK adults. This dual system persists because it's what people are familiar with and prefer to use.
How many pounds are in a stone?
There are exactly 14 pounds in one stone. This fixed relationship makes conversions between stone and pounds straightforward. So 1 stone 7 pounds equals 21 pounds total, or approximately 9.5 kilograms.
What is the healthy weight range in stone?
For most UK adults, a healthy BMI sits between 18.5 and 24.9. For someone 5ft 8in (173cm) tall, the healthy weight range is approximately 8 stone 10 lbs to 11 stone 10 lbs. Use our free BMI calculator to find your personal healthy weight range based on your height and current weight.
Is stone used anywhere else in the world?
Stone is primarily used in the UK, Ireland, and some Commonwealth countries like Australia and South Africa — though Australia is gradually shifting to kilograms. Most countries worldwide use only the metric system (kilograms). This makes stone unique to British and Irish weight discussions.
How do I convert my weight to stone if I only know it in kilograms?
Divide your weight in kilograms by 6.35. For example, 80kg ÷ 6.35 = approximately 12 stone 8 pounds. Our free weight converter tool above does this calculation instantly — just enter your weight in kg and select stone as your target unit.
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.