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 13.5 Stones in Kilograms?
13.5 stones is equal to approximately 85.7 kilograms. This conversion uses the standard UK to metric formula: one stone equals 6.35029 kg. If you're tracking your weight using different measurement systems, understanding both stone and kilogram measurements is essential for NHS health guidance and weight management. Use our free weight converter above to switch between metric and imperial units instantly, and check how this weight relates to your personal health using our BMI calculator.
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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.
How to Convert 13.5 Stone to Kilograms
Converting stone to kilograms is straightforward using the standard conversion factor. One stone equals exactly 6.35029 kg. To convert 13.5 stone to kg, multiply: 13.5 × 6.35029 = 85.7 kg (rounded to one decimal place).
The reverse calculation works the same way: 85.7 kg ÷ 6.35029 = 13.5 stone. Most UK health services, including the NHS, use kilograms for clinical measurements, while many UK adults still prefer stone and pounds for personal weight tracking. Having both measurements helps you understand your weight in the context of NHS health guidance and weight management advice, whether you're discussing your health with your GP or using digital health tools.
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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.
BMI and Healthy Weight at 13.5 Stone (85.7 kg)
At 13.5 stone (85.7 kg), your BMI depends on your height. For example, if you are 5ft 9in (175 cm) tall, a weight of 13.5 stone gives a BMI of approximately 26.6, which falls in the overweight category according to NHS guidelines (BMI 25–29.9). The healthy weight range for this height is 60–76 kg (9st 6lbs–11st 13lbs).
If your BMI falls outside the healthy range, small changes can make a meaningful difference to your health outcomes. The NHS recommends losing weight at a sustainable rate of 0.5–1 kg per week. Try our free BMI calculator above to check your personal BMI instantly, and speak with your GP about appropriate weight management strategies for your individual health situation.
- 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.
Is 13.5 stone overweight?
Whether 13.5 stone (85.7 kg) is overweight depends on your height. Using NHS BMI categories, at 5ft 9in it gives a BMI of 26.6 (overweight), but at 6ft 2in it gives a BMI of about 23 (healthy weight). Use our free BMI calculator to check your personal status based on your exact height and weight.
How do I convert stone to kg accurately?
Multiply the stone amount by 6.35029. For 13.5 stone: 13.5 × 6.35029 = 85.7 kg. Our free weight converter above performs this instantly and also converts to pounds. Most conversions are rounded to one decimal place for practical use.
What's the healthy weight range at my height if I weigh 13.5 stone?
The healthy weight range depends on your height. At 5ft 9in, healthy weight is 60–76 kg (9st 6lbs–11st 13lbs). At 5ft 6in, it's 55–70 kg (8st 8lbs–11st 0lbs). Consult our BMI calculator with your specific height for an accurate range aligned with NHS guidance.
Why do UK doctors use kilograms instead of stone?
NHS clinical services use kilograms because it's the international standard for healthcare measurements and makes calculations clearer for medical purposes. However, many UK patients prefer stone for personal tracking. Having both measurements helps with communication with your GP and understanding your health data.
Can weight alone tell me if I'm healthy?
Weight is one health indicator, but BMI has limitations — it doesn't account for muscle mass or where fat is stored. The NHS also recommends measuring waist circumference. For a complete picture of your health, speak with your GP, who can assess your individual risk factors and recommend appropriate weight management strategies.
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.