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 12 lbs in Kilograms?
13st 12 lbs converts to approximately 87.99 kg. This is a straightforward weight conversion using the standard UK to metric formula. Whether you're tracking your weight for health reasons, following NHS health guidance, or simply need to convert between imperial and metric measurements, understanding your weight in both units is helpful. Use our free weight converter above to switch between stone, pounds, and kilograms instantly.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
UK Health Context for 87.99 kg
At 87.99 kg, your weight classification depends on your height. For an average UK adult woman (around 163 cm or 5ft 4in), a weight of 87.99 kg results in a BMI of approximately 33.1, which falls into the obese (Class I) category according to NHS guidelines. For an average UK adult man (around 175 cm or 5ft 9in), the same weight gives a BMI of around 28.7, which is overweight. These are NHS classifications and individual health depends on many factors beyond BMI alone, including muscle mass, waist circumference, and overall fitness. Our free BMI calculator above can show you your precise BMI based on your actual height and weight. Always remember that BMI is a useful screening tool but has limitations — it doesn't distinguish between muscle and fat.
Clinically BackedWeight Loss
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.
Using UK Health Tools and Getting Support
To understand what your weight of 87.99 kg means for your personal health, start by calculating your BMI using the free calculator on this page. If you have concerns about your weight or health, your GP can provide tailored advice and discuss weight management options aligned with NHS health guidance. For sustainable weight loss, the NHS recommends aiming for 0.5 to 1 kg per week through balanced diet and physical activity. If you're tracking progress, our free progress tracker can help log your weight over time. In the UK, specialist weight management services are available through the NHS for those with a BMI of 30 or above, or 27 or above with weight-related health conditions.
- 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 13st 12 lbs in kg exactly?
13st 12 lbs equals 87.99 kg. To calculate: (13 stone × 6.35029) + (12 lbs × 0.453592) = 87.99 kg. You can use our free weight converter above to instantly switch between stone, pounds, and kilograms.
Is 87.99 kg a healthy weight?
Whether 87.99 kg is healthy depends entirely on your height. Use the free BMI calculator on this page to check your personal BMI. For NHS guidance, a healthy BMI is 18.5 to 24.9 for most adults, though lower thresholds apply for South Asian, Chinese, Black African, or Black Caribbean heritage.
How do I convert 13st 12 lbs to kg?
Multiply the stone by 6.35029, then add (pounds × 0.453592). So: (13 × 6.35029) + (12 × 0.453592) = 82.5537 + 5.4431 = 87.99 kg. Our weight converter tool above does this instantly.
What weight loss targets should I aim for?
The NHS recommends losing 0.5 to 1 kg per week for sustainable results. This typically requires a calorie deficit of around 500 kcal per day. Always speak to your GP before starting any weight loss programme, especially if you have existing health conditions.
Where can I get weight management support in the UK?
Start by discussing weight with your GP, who can refer you to NHS tier 2 or tier 3 weight management services depending on your BMI and health. These services offer behaviour change support and, where appropriate, prescription weight loss medication as part of a comprehensive programme.
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.