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 13st 6lb in kg?
13 stone 6 pounds equals approximately 85.7 kilograms. This conversion uses the standard UK to metric formula: stone is multiplied by 6.35029, and pounds are multiplied by 0.453592, then added together. At this weight, your BMI and health context depend on your height — use our free BMI calculator above to check where you stand against NHS guidelines. Understanding your weight in both UK and metric measurements helps when discussing health with your GP or reviewing NHS health advice.
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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 13st 6lb to Kilograms
The conversion formula:
- 13 stone × 6.35029 = 82.55 kg
- 6 pounds × 0.453592 = 2.72 kg
- Total: 82.55 + 2.72 = 85.27 kg (or approximately 85.3 kg when rounded)
For quick reference, use our free weight converter above to switch between stone, pounds, and kilograms instantly. This conversion is exact and aligns with NHS measurement standards used across UK healthcare. Whether you're tracking your weight for health monitoring, discussing measurements with your GP, or comparing your weight to NHS guidance, having both metric and imperial figures is useful. The metric measurement (kg) is what you'll typically see in clinical settings and health calculators.
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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.
13st 6lb in Health Context
At 85.7 kg, your health context depends entirely on your height. For example, if you're 1.75m tall (5ft 9in), a weight of 85.7kg gives a BMI of approximately 28 — which falls in the overweight range according to NHS guidelines. If you're taller, your BMI would be lower; if shorter, your BMI would be higher. Check your personal BMI using our free calculator above to understand where you stand against NHS healthy weight recommendations (BMI 18.5 to 24.9). Even modest weight loss of 5–10% of body weight can bring meaningful health benefits including improved blood pressure, better blood sugar control, and reduced joint strain.
- 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 13st 6lb overweight?
It depends on your height. At 13st 6lb (85.7kg), your BMI classification varies based on how tall you are. Use our free BMI calculator on this page to check your specific BMI against NHS categories. For most adults of average height, 13st 6lb would fall in the overweight range, but this is individual.
How many kg is 13 stone exactly?
13 stone equals 82.55 kg exactly. Each stone = 6.35029 kg. If you add 6 pounds (2.72 kg), the total is 85.27 kg, which we round to 85.3 kg for practical purposes.
What is my healthy weight range at this weight?
Your healthy weight range depends on your height. Use our free BMI calculator and weight converter above to find your healthy weight range according to NHS guidelines. For most adults, a healthy BMI is between 18.5 and 24.9. Your GP can also advise on healthy weight goals for your individual health situation.
How can I track weight changes from stone to kg?
Our free progress tracker lets you log your weight in either stone or kg and monitor changes over time. Tracking consistently — whether in metric or imperial — helps you see progress and stay motivated. You can switch between units anytime using our weight converter.
Does NHS use stone or kg for health advice?
The NHS primarily uses kilograms (kg) in clinical settings and official guidelines, but UK adults often think in stone and pounds. Both are equally valid. Use our weight converter to switch between units, and check your BMI using either measurement with our free calculator above.
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.