What is a Weight Converter?
A weight converter (more accurately called a mass converter) is a tool that transforms measurements of mass from one unit to another. Mass measures the amount of matter in an object, and while we commonly call it "weight" in everyday language, weight technically refers to the gravitational force on that mass.
This converter supports metric units (kilograms, grams, metric tons) and imperial units (pounds, ounces, stones), enabling conversions between the two systems used worldwide.
How Does Weight Conversion Work?
Weight conversion uses fixed ratios between units. The process involves:
- Convert to base unit: First, the input value is converted to kilograms (the SI base unit for mass).
- Convert to target unit: The kilogram value is then converted to the desired output unit.
- Apply conversion factor: Each unit has an exact relationship to the kilogram defined by international standards.
Conversion Formulas
All weight conversions use the kilogram as the base unit. Here are the exact conversion factors:
1 metric ton (t) = 1,000 kilograms
1 kilogram (kg) = 1,000 grams
1 gram (g) = 1,000 milligrams
Imperial to Metric (exact by definition):
1 pound (lb) = 0.45359237 kg (exactly)
1 ounce (oz) = 28.349523125 g (1/16 pound)
1 stone (st) = 6.35029318 kg (14 pounds)
1 US ton (short ton) = 907.18474 kg (2,000 pounds)
1 UK ton (long ton) = 1,016.0469088 kg (2,240 pounds)
Common Weight Conversions
Here are the most frequently used conversion factors:
- Kilograms to Pounds: Multiply by 2.20462 (1 kg = 2.20462 lb)
- Pounds to Kilograms: Multiply by 0.453592 (1 lb = 0.453592 kg)
- Ounces to Grams: Multiply by 28.3495 (1 oz = 28.3495 g)
- Grams to Ounces: Divide by 28.3495 (1 g = 0.03527 oz)
- Stones to Kilograms: Multiply by 6.35029 (1 st = 6.35029 kg)
- Kilograms to Stones: Divide by 6.35029 (1 kg = 0.1575 st)
Benefits of Using This Converter
- Instant results: Conversions happen in real-time as you type.
- High precision: Uses exact conversion factors from international standards.
- Comprehensive units: Supports 9 weight units covering metric, imperial, and specialized units.
- No installation required: Works directly in your browser.
- Privacy focused: All calculations happen locally - no data sent to servers.
Understanding Different Weight Units
Kilogram (kg): The SI base unit of mass, defined by the Planck constant since 2019. Previously defined by the International Prototype of the Kilogram in Paris.
Pound (lb): The primary unit of mass in the US customary system. Defined as exactly 0.45359237 kg since 1959.
Stone (st): A British unit equal to 14 pounds, commonly used in UK and Ireland for body weight.
Metric Ton (t): Also called tonne, equals 1,000 kg. Used globally for large masses in shipping and industry.
Frequently Asked Questions
How many pounds are in a kilogram?
There are approximately 2.20462 pounds in 1 kilogram. For quick mental math, you can double the kg value and add 10% to get a rough pound estimate.
How do I convert my body weight from kg to stones and pounds?
Divide your weight in kg by 6.35029 to get stones. The remainder converts to pounds by multiplying by 14. For example, 70 kg = 11 stone 0.2 pounds.
What's the difference between a metric ton and a US ton?
A metric ton (tonne) equals 1,000 kg. A US ton (short ton) equals 2,000 pounds or about 907 kg. A UK ton (long ton) equals 2,240 pounds or about 1,016 kg.
Why is a pound abbreviated as "lb"?
The abbreviation "lb" comes from the Latin word "libra," which means "scales" or "balance." The Roman libra was a unit of weight that eventually evolved into the modern pound.
How accurate is this converter?
This converter uses the exact conversion factors defined by the International Bureau of Weights and Measures (BIPM). Results are accurate to at least 6 decimal places.
What is an avoirdupois ounce?
The avoirdupois ounce (28.3495 g) is the standard ounce used in everyday commerce in the US and UK. It differs from the troy ounce (31.1035 g) used for precious metals.