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
4 Stone 15 Pounds to Kilograms
4 stone 15 pounds (4st 15lbs) converts to approximately 31.25 kilograms (31.3 kg). This UK health guide uses the exact conversion formula: multiply stone by 6.35029 and pounds by 0.453592, then add together. At this weight, understanding your BMI and healthy weight range matters for your long-term health. MyWeightCheck's free weight converter makes it easy to switch between UK and metric measurements instantly. Whether you're tracking progress, comparing health data, or simply need NHS guidance on weight management, knowing your weight in kilograms helps you access health information across different systems.
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.
BMI and Health Context at This Weight
At 31.25 kg, your weight is significantly below the UK adult average (which sits around 70–80 kg depending on height). Your BMI depends entirely on your height. For example, if you're 5ft 4in (163cm), a BMI of 31.25 kg would give approximately 11.8 — well within the healthy weight range of 18.5–24.9 according to NHS guidance. If you're 5ft (152cm), the same weight would result in a BMI around 13.5, which falls in the underweight category.
Important considerations:
- BMI alone doesn't account for muscle mass, bone density, or where fat is stored
- Very low weight may indicate insufficient nutrition — speak with your GP if you're concerned
- Ethnicity affects health risk at the same weight — South Asian and Black African adults may have different thresholds
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 MyWeightCheck for Weight Tracking
MyWeightCheck offers free tools to help you understand your weight in both UK and metric measurements. Our BMI calculator instantly shows whether your weight sits in a healthy range for your height, using NHS thresholds. Our progress tracker lets you log weight changes over time and spot trends. The free weight converter removes the maths — simply enter 4 stone 15 pounds and see the kilogram equivalent instantly.
If you're managing weight for health reasons, NHS health advice recommends discussing targets with your GP. They can provide personalised weight management guidance based on your medical history and health goals.
- 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 4 stone 15 pounds in kilograms?
4 stone 15 pounds equals approximately 31.25 kilograms (31.3 kg). Use the conversion: (4 × 6.35029) + (15 × 0.453592) = 31.25 kg. MyWeightCheck's free weight converter calculates this instantly.
Is 4 stone 15 pounds a healthy weight?
It depends on your height. At this weight, your BMI — calculated using NHS guidelines — tells you whether it falls in the healthy range (18.5–24.9). A GP or our free BMI calculator can assess what's healthy for you personally.
Why convert stone and pounds to kilograms?
Most NHS health data, clinical measurements, and international health information use kilograms. Converting between UK and metric measurements helps you compare your weight across different health systems and resources.
How can I track my weight properly?
MyWeightCheck offers a free progress tracker to log weight changes over time. Recording in both stone and kilograms helps you spot trends and understand your progress. Always discuss weight goals with your GP for personalised guidance.
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.