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
13.5 Stone to Kilos — What's Your BMI?
13.5 stone is equivalent to 85.7 kilograms. Your BMI at this weight depends entirely on your height — the same weight can be healthy for a tall person but overweight for someone shorter. Use our free BMI calculator above to find your exact BMI, or see the examples below to understand where this weight falls across different heights and NHS categories.
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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.
BMI at 13.5 Stone — Height-by-Height Guide
13.5 stone (85.7kg) gives different BMI values depending on your height:
- 5ft (152cm): BMI 37.1 — Obese Class II
- 5ft 4in (163cm): BMI 32.5 — Obese Class I
- 5ft 8in (173cm): BMI 28.7 — Overweight
- 5ft 10in (178cm): BMI 27.3 — Overweight
- 6ft (183cm): BMI 25.5 — Healthy weight
- 6ft 2in (188cm): BMI 24.1 — Healthy weight
To convert kilograms to stone and understand your personal BMI, enter your height into our free BMI calculator. Remember that BMI is a screening tool — it doesn't account for muscle mass or where fat is stored, so your GP can give you personalised health advice based on your individual circumstances.
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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.
NHS Weight Categories & BMI Limitations
According to NHS guidelines, a healthy BMI range is 18.5 to 24.9. At 13.5 stone, whether you fall into this range depends on your height. BMI has important limitations: it doesn't distinguish between muscle and fat, so athletes may have a high BMI despite low body fat. It also doesn't account for age, bone density, or where fat is stored. For South Asian, Chinese, Black African, or Black Caribbean adults, the NHS recommends lower BMI thresholds — healthy weight begins at BMI 18.5 but overweight starts at BMI 23.0. Use the weight converter on this page to check your weight in different units, and speak to your GP if you'd like personalised guidance about what weight range is healthy for you.
- 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 13.5 stone in kilograms?
13.5 stone equals 85.7 kilograms. To convert stone to kilos, multiply by 6.35029. This weight is significant — whether it's healthy depends on your height, age, and body composition. Use our weight converter to switch between metric and imperial measurements instantly.
Is 13.5 stone overweight?
It depends on your height. At 5ft 8in, 13.5 stone gives a BMI of 28.7 (overweight). At 6ft, the same weight gives a BMI of 25.5 (healthy). Our free BMI calculator shows your exact category based on your height and weight.
What's a healthy weight in stone for my height?
A healthy BMI is 18.5 to 24.9 according to NHS guidelines. For example, at 5ft 8in, healthy weight is roughly 8st 5lbs to 11st 3lbs. At 6ft, it's about 9st 4lbs to 12st 6lbs. Your GP can advise on what's healthy for you personally.
Can BMI be inaccurate?
Yes. BMI doesn't account for muscle mass, so athletes may have a high BMI but low body fat. It also doesn't reflect where fat is stored or account for age and bone density. Waist circumference is another useful measurement — the NHS recommends staying below 94cm for men and 80cm for women.
How do I know if I need to lose weight?
Your GP can assess your health based on BMI, waist circumference, and overall health status — not weight alone. If you're concerned, book a check-up. Our progress tracker can help you monitor changes over time if your GP recommends weight management.
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.