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
8.7 Kg in Pounds — What's Your BMI?
8.7 kilograms converts to 19.2 pounds (or 1 stone 5.2 pounds in UK measurements). However, your BMI depends entirely on your height — the same weight gives a very different BMI result for a person who is 160cm tall versus 180cm tall. This guide shows you what BMI 8.7kg produces at different heights, and where each falls on NHS health guidelines. Use our free BMI calculator above to find your exact BMI 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.
8.7 Kg BMI at Different Heights
At 8.7kg, here's how your BMI changes based on your height:
- 160cm (5ft 3in): BMI of 33.9 — falls in the obese (Class I) category
- 165cm (5ft 5in): BMI of 31.9 — falls in the obese (Class I) category
- 170cm (5ft 7in): BMI of 30.1 — falls in the obese (Class I) category
- 175cm (5ft 9in): BMI of 28.4 — falls in the overweight category
- 180cm (5ft 11in): BMI of 26.8 — falls in the overweight category
- 185cm (6ft 1in): BMI of 25.4 — falls in the healthy weight category
These BMI figures use the NHS standard categories. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds may apply — your GP can advise on what's appropriate for you.
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.
NHS BMI Categories and Important Limitations
According to NHS guidelines, a healthy BMI is between 18.5 and 24.9. The BMI categories are: underweight (below 18.5), healthy weight (18.5–24.9), overweight (25–29.9), and obese (30 and above).
However, BMI has important limitations — it doesn't distinguish between muscle and fat, so athletes may have a high BMI but low body fat. BMI also doesn't account for where fat is stored or your overall fitness level. For a complete health picture, your GP may also consider your waist circumference and other health markers. Use our free weight converter to check your weight in different units, and speak with your GP about what a healthy weight range means for you personally.
- 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 8.7 kilograms in pounds exactly?
8.7 kilograms equals 19.19 pounds (often rounded to 19.2 lbs). In stone and pounds, this is 1 stone and 5.2 pounds. To convert kg to stone, you divide by 6.35029. Our free weight converter above makes this instant.
Is a BMI of 31.9 at 165cm considered overweight or obese?
A BMI of 31.9 falls into the obese (Class I) category according to NHS guidelines, which classify BMI 30.0–34.9 as obese Class I. This is above the healthy range of 18.5–24.9. Your GP can discuss what this means for your individual health.
Does BMI change if I'm very muscular?
Yes — BMI doesn't distinguish muscle from fat. If you have high muscle mass, your BMI may appear higher than your actual body fat percentage suggests. This is one of BMI's main limitations. Your GP can assess your overall health beyond BMI alone.
What's the healthy weight range at 170cm?
At 170cm, a healthy BMI falls between 18.5 and 24.9, which corresponds to a weight range of approximately 53–72 kg (8st 5lbs to 11st 4lbs). At 8.7kg you'd be well above this range. Our BMI calculator helps you find your personal healthy weight range.
How can I use this information with my GP?
Take this BMI information to your GP appointment as context for a health conversation. Your GP will consider your BMI alongside other factors like waist circumference, family history, fitness level, and any health conditions. They can advise on whether weight management might benefit your health.
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.