Stones to Kilograms Converter
Convert UK weight to metric instantly. Accurate, simple, free.
Common values: 1, 5, 10, 15, 20 stones
Note: 1 stone = 14 pounds. Add up to 13.99 extra pounds.
Common Weight Conversions
| Stones | Kilograms | Pounds | Common Usage |
|---|---|---|---|
| 1 st | 6.35 kg | 14 lb | Small weight loss |
| 5 st | 31.75 kg | 70 lb | Child’s weight |
| 10 st | 63.50 kg | 140 lb | Average adult |
| 15 st | 95.25 kg | 210 lb | Heavier adult |
| 20 st | 127.01 kg | 280 lb | Weight limit |
Important: Medical Accuracy
For medical dosing and clinical records, use the exact conversion: 1 stone = 6.35029318 kg. Rounding to 6.35 kg is acceptable for most purposes, but exact calculations may be needed for medication.
Stones to Kilograms Conversion Result
How Stones to Kilograms Conversion Works
Converting stones to kilograms involves a precise mathematical conversion that bridges UK imperial measurements with the international metric system. This conversion is particularly important for healthcare, fitness tracking, and international communication where different measurement systems are used.
Exact Conversion Formula:
kilograms = stones × 6.35029318
This exact factor comes from: 1 stone = 14 pounds, and 1 pound = 0.45359237 kg
The Exact Conversion Mathematics
One stone equals exactly 6.35029318 kilograms. This precise conversion is derived from two standardized conversions: 1 stone = 14 pounds, and 1 pound = 0.45359237 kilograms. Multiplying these gives us the exact stone-to-kilogram conversion factor.
Country-Specific Usage and Examples
United Kingdom Usage
In the UK, people commonly describe personal weight in stones and pounds in everyday conversation. However, the healthcare system officially uses kilograms for medical records, prescriptions, and clinical measurements. This creates a constant need for conversion between the two systems.
- Medical records: kilograms for accuracy, stones for patient communication
- Pharmacy: medication dosing calculated in kilograms
- Fitness industry: gym equipment often shows both systems
- Retail: food products labeled in metric, people think in stones
- Media: weight loss stories often mention stones lost
UK Healthcare Example:
A patient says they weigh 12 stone 8 pounds. The nurse converts this to kilograms: (12 × 6.35029318) + (8 × 0.45359237) = 76.20 + 3.63 = 79.83 kg. This exact weight is recorded for medication calculations.
United States Usage
Americans do not use stones at all. They measure weight exclusively in pounds. However, Americans may need to convert stones to kilograms when:
- Reading international medical research (often in kilograms)
- Understanding UK health information or news stories
- Communicating with UK healthcare providers
- Participating in international sports with metric weight classes
- Traveling to countries using the metric system
Canada Usage
Canada officially uses the metric system (kilograms) but many people understand pounds from American media and older measurement systems. Stones are rarely encountered except in UK contexts. Canadians might need conversions when:
- Reading British publications or watching UK media
- Communicating with UK relatives about health matters
- Understanding historical weight references
- Working with UK-based medical information
Canadian Example:
A Canadian reads a UK article about a person who lost 3 stone. Converting: 3 × 6.35029318 = 19.05 kg. They understand this as approximately 42 pounds of weight loss.
Australia Usage
Australia exclusively uses the metric system. Stones are only encountered in historical contexts or UK references. Australians converting stones typically need it for:
- Understanding British weight references in media
- Academic research involving UK historical data
- Medical collaboration with UK institutions
- Personal communication with UK contacts
Practical Applications for Different Users
For Medical and Healthcare Professionals
Accurate weight conversion is critical in healthcare for proper medication dosing, treatment planning, and patient monitoring. Even small errors can lead to incorrect dosages.
Medical Tip: Always use the exact conversion (6.35029318 kg per stone) for medication calculations. For patient communication, rounding to 6.35 kg per stone is acceptable and easier to understand.
For Fitness and Weight Management
People tracking weight loss or fitness progress often need to convert between stones and kilograms. Many fitness apps and scales allow switching between measurement systems.
Fitness Example:
A person wants to lose 2 stone for a wedding. Converting to metric: 2 × 6.35029318 = 12.70 kg. They set a goal to lose 12.7 kilograms over 6 months, approximately 0.5 kg per week.
For Sports and Athletics
International sports competitions use kilograms for weight classes. UK athletes accustomed to stones need to convert for competition requirements and training monitoring.
For Travel and International Communication
When traveling between countries using different measurement systems, or when communicating internationally about health matters, conversion between stones and kilograms becomes necessary.
Common Questions About Stone to Kilogram Conversion
Why is the conversion factor 6.35029318 exactly?
This exact number comes from the international standardization of the pound (0.45359237 kg) multiplied by 14 (pounds in a stone). The calculation is: 14 × 0.45359237 = 6.35029318. This precision ensures consistency in international trade and science.
How do I convert stones and pounds to kilograms?
First convert stones to kilograms (stones × 6.35029318), then convert pounds to kilograms (pounds × 0.45359237), and add them together. Example: 10 stone 7 pounds = (10 × 6.35029318) + (7 × 0.45359237) = 63.50 + 3.18 = 66.68 kg.
What’s the quick mental calculation method?
For rough estimates: multiply stones by 6.35. Example: 10 stone × 6.35 = 63.5 kg (exact: 63.5029318 kg). For stones and pounds: multiply stones by 6.35, multiply pounds by 0.45, then add. This gives results accurate within 0.1% for most purposes.
Why do UK hospitals use kilograms if people use stones?
The UK healthcare system officially adopted the metric system for accuracy and international standardization. Kilograms provide more precise measurements for medication dosing and clinical calculations. However, healthcare professionals often convert to stones when communicating with patients who are more familiar with that system.
How accurate do I need to be for weight loss tracking?
For personal weight loss tracking, rounding to the nearest 0.1 kg (100 grams) is usually sufficient. This means using 6.35 kg per stone is perfectly adequate. The difference between 6.35 and 6.35029318 is only 0.0046%, negligible for weight monitoring.
Technical Details and Medical Precision
The exact conversion is based on international standards established in 1959:
1 pound (avoirdupois) = 0.45359237 kilograms (international standard)
1 stone = 14 pounds (historical UK standard)
Therefore: 1 stone = 14 × 0.45359237 = 6.35029318 kilograms (exact)
This standardization ensures that medical dosages, scientific research, and international trade use consistent measurements. The exact conversion is particularly important for pediatric medications, chemotherapy drugs, and other treatments where precise dosing is critical.
Historical Context and Modern Usage
The stone was officially abolished for trade in the UK in 1985 under the Weights and Measures Act. However, it remains in common use for body weight due to cultural tradition. The metric system is now the legal standard for all official purposes, creating this dual-system reality in everyday UK life.
Common Conversion Mistakes to Avoid
Critical Errors to Watch For:
- Using 6.3 or 6.4 instead of 6.35 for approximate conversions
- Forgetting to convert additional pounds when present
- Confusing stones with kilograms in medical contexts
- Using approximate conversions for medication calculations
- Assuming 1 stone equals 7 kg (a common misconception)
Verification Method
Always verify your conversion by doing the reverse calculation. If 10 stone = 63.5029318 kg, then 63.5029318 kg should convert back to 10 stone (63.5029318 ÷ 6.35029318 = 10 exactly). This catches calculation errors, especially important for medical applications.
Quick Reference Table for Common Weights:
Special Applications and Considerations
Medication Dosing Calculations
For accurate medication dosing, precise conversions are essential. Most medications are dosed based on body weight in kilograms:
- Pediatric medications: calculated as mg per kg of body weight
- Chemotherapy drugs: extremely precise weight-based dosing
- Anesthesia: calculated based on exact body weight
- Antibiotics: weight-based dosing for optimal effectiveness
Medication Example:
A drug is prescribed at 5 mg per kg. A patient weighs 13 stone 2 pounds. Exact conversion: (13 × 6.35029318) + (2 × 0.45359237) = 82.55 + 0.91 = 83.46 kg. Dosage: 83.46 × 5 = 417.3 mg daily.
Weight Loss and Fitness Goals
When setting and tracking weight loss goals in the UK:
Losing 1 stone = losing 6.35 kg = 14 pounds
Losing half a stone = 3.175 kg = 7 pounds
Common goal: lose 2 stone (12.7 kg or 28 pounds)
Healthy rate: 0.5-1 kg (1-2 pounds) per week
Clinical Guidelines and BMI Calculation
Body Mass Index (BMI) calculations require weight in kilograms:
- BMI = weight (kg) ÷ height² (m²)
- Underweight: BMI less than 18.5
- Normal weight: BMI 18.5-24.9
- Overweight: BMI 25-29.9
- Obese: BMI 30 or greater
Sports Weight Classes
International sports use metric weight classes that UK athletes must convert to:
Boxing Example:
A UK boxer competing internationally needs to make the 75 kg weight class. Converting from stones: 75 ÷ 6.35029318 = 11.81 stone. This is approximately 11 stone 11 pounds (11 × 14 + 11 = 165 pounds).
Pregnancy and Baby Weight Tracking
In the UK, baby weights are tracked in metric for medical records but often discussed in pounds:
Newborn: 3.4 kg = 7 pounds 8 ounces
3 months: 6 kg = 13 pounds 4 ounces
6 months: 7.5 kg = 16 pounds 8 ounces
1 year: 10 kg = 22 pounds
About This Conversion Tool
This stones to kilograms converter provides instant, accurate conversions using the exact international standard factor (6.35029318 kg per stone). Designed for healthcare professionals, UK residents, fitness enthusiasts, and anyone needing to convert between UK weight measurements and the metric system. The tool handles stones and additional pounds, and provides both kilograms and grams for practical use. No registration required, no tracking, just precise calculations when you need them. Works completely offline after loading.