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Weight & Mass Converter UPDATED
Convert between 40+ weight and mass units instantly. Support for metric, imperial, scientific, regional, and industrial measurement systems with precise calculations.
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How to Use Weight & Mass Converter
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2
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Convert Weight & Mass
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Conversion Result
1 kg = 1000 g
Precision: 15 decimal places
Metric System
Kilogram (kg)
SI base unit
Gram (g)
1/1000 kilogram
Milligram (mg)
1/1000 gram
Microgram (µg)
1/1,000,000 gram
Tonne (t)
1000 kilograms
Hectogram (hg)
100 grams
Imperial & US Units
Pound (lb)
16 ounces
Ounce (oz)
1/16 pound
Stone (st)
14 pounds
US Ton
2000 pounds
UK Ton
2240 pounds
Grain (gr)
1/7000 pound
Regional & Cultural
Carat (ct)
200 milligrams
Tola
South Asian unit
Tael
Chinese unit
Momme
Japanese pearl weight
Troy Ounce
Precious metals
Pennyweight
1/20 troy ounce
Scientific Units
Atomic Mass (u)
Carbon-12 standard
Dalton (Da)
Atomic mass unit
Electron Mass
Mass of electron
Planck Mass
Quantum scale
Slug
Imperial mass unit
Instant Conversion
Real-time calculations with high precision for all 40+ supported units simultaneously.
Scientific Accuracy
Precise conversion factors with up to 15 decimal places for scientific applications.
Global Coverage
Support for metric, imperial, scientific, regional, and industrial measurement systems.
Historical Context
Learn about the origins and usage contexts of different measurement systems worldwide.
Frequently Asked Questions
What is the difference between weight and mass?
Mass is the amount of matter in an object, while weight is the force exerted on that mass by gravity. Mass remains constant regardless of location, but weight changes with gravitational pull.
Why is kilogram the SI base unit for mass?
The kilogram was chosen as the SI base unit because it provides a practical, reproducible standard for mass measurements. It was originally defined as the mass of one liter of water at 4°C.
How accurate are the conversions?
Our conversions use internationally recognized standards and conversion factors with precision up to 15 decimal places, ensuring accuracy suitable for scientific and commercial applications.
What is a troy ounce vs regular ounce?
A troy ounce (31.1035g) is used for precious metals and is heavier than a regular avoirdupois ounce (28.3495g). There are 12 troy ounces in a troy pound versus 16 regular ounces in a pound.
How do I convert between metric tons and US tons?
One metric ton equals 1000 kilograms (2204.62 pounds), while one US ton (short ton) equals 2000 pounds. Therefore, 1 metric ton ≈ 1.10231 US tons.
What is the Planck mass used for?
The Planck mass (about 21.76 micrograms) is a fundamental unit in quantum mechanics and theoretical physics, derived from fundamental constants and used in Planck scale physics.
Complete Guide to Weight and Mass Measurement
Understanding weight and mass measurement systems is essential for science, commerce, and daily life. This comprehensive guide covers historical contexts, scientific principles, and practical applications of mass measurement across different cultures and disciplines.
Fundamental Concepts: Mass vs Weight
Mass: The Quantity of Matter
Mass is a fundamental property of physical bodies that measures their resistance to acceleration (inertia) and determines the strength of their mutual gravitational attraction. It is an intrinsic property that remains constant regardless of location in the universe.
The SI unit for mass is the kilogram (kg), defined since 2019 by fixing the numerical value of the Planck constant (h) to 6.62607015×10⁻³⁴ when expressed in the unit J⋅s. This definition ensures extreme precision and reproducibility.
Weight: The Force of Gravity
Weight is the force exerted on a mass by a gravitational field. It varies with location - an object weighs less on the Moon than on Earth, despite having the same mass. Weight is calculated as mass multiplied by gravitational acceleration (W = m × g).
This distinction is crucial in physics and engineering. While everyday language often uses "weight" to mean mass, scientific contexts maintain the precise distinction between these concepts.
Historical Development of Mass Measurement
The concept of mass measurement dates back to ancient civilizations. Early systems used natural references like grains of wheat or barley. The ancient Egyptians used the deben, while Mesopotamian civilizations developed sophisticated weight systems for trade.
The modern metric system emerged during the French Revolution, with the kilogram originally defined as the mass of one liter of water at 4°C. This established a decimal-based system that eventually evolved into the International System of Units (SI).
International System of Units (Metric)
Kilogram: The Base Unit
The kilogram serves as the foundation of mass measurement in the metric system. Its current definition, based on fundamental constants, represents a significant advancement from the original physical artifact (International Prototype of the Kilogram) used from 1889 to 2019.
Key metric units include:
- Gram (g): 1/1000 of a kilogram, suitable for small measurements
- Milligram (mg): 1/1000 of a gram, used in medicine and chemistry
- Microgram (µg): 1/1,000,000 of a gram, for trace measurements
- Tonne (t): 1000 kilograms, for large-scale measurements
Metric Prefix System
The metric system employs decimal prefixes to indicate multiples and submultiples of units. This systematic approach simplifies calculations and conversions across different scales:
| Prefix | Symbol | Factor | Example |
|---|---|---|---|
| micro | µ | 10⁻⁶ | microgram (µg) |
| milli | m | 10⁻³ | milligram (mg) |
| centi | c | 10⁻² | centigram (cg) |
| deci | d | 10⁻¹ | decigram (dg) |
| hecto | h | 10² | hectogram (hg) |
| kilo | k | 10³ | kilogram (kg) |
| mega | M | 10⁶ | megagram (Mg) |
Imperial and US Customary Systems
Historical Development
The Imperial system evolved from earlier English units standardized in the British Weights and Measures Act of 1824. The US Customary system developed independently after American independence but shares common origins with the Imperial system.
Key differences emerged, particularly in volume measurements, though mass units remained largely consistent between the two systems until the 20th century.
Core Imperial/US Mass Units
| Unit | Equivalent | Metric Equivalent | Usage Context |
|---|---|---|---|
| Grain (gr) | 1/7000 lb | 64.79891 mg | Precision measurements, ammunition |
| Ounce (oz) | 1/16 lb | 28.349523125 g | General purpose, cooking |
| Pound (lb) | 16 oz | 453.59237 g | Common weight measurement |
| Stone (st) | 14 lb | 6.35029318 kg | Body weight (UK) |
| US Ton | 2000 lb | 907.18474 kg | Commercial, industrial (US) |
| UK Ton | 2240 lb | 1016.0469088 kg | Commercial, industrial (UK) |
Regional Variations
While the pound and ounce are consistent across Imperial and US systems, larger units show significant variation. The US hundredweight (100 lb) differs from the Imperial hundredweight (112 lb), and ton definitions vary between systems.
These differences are important in international trade and engineering, where precise conversions prevent costly errors in specifications and contracts.
Scientific Mass Units
Atomic Scale Measurements
Scientific research requires extremely precise mass measurements at atomic and subatomic scales. Key units include:
- Atomic Mass Unit (u): Defined as 1/12 the mass of a carbon-12 atom, approximately 1.66053906660×10⁻²⁷ kg
- Dalton (Da): Essentially equivalent to the atomic mass unit, used in biochemistry and molecular biology
- Electron Mass (me): The mass of an electron, approximately 9.1093837015×10⁻³¹ kg
Theoretical Physics Units
In theoretical physics, mass is sometimes expressed in natural units derived from fundamental constants:
- Planck Mass: Derived from fundamental constants (ħ, c, G), approximately 21.76 micrograms
- Solar Mass: Astronomical unit equal to the mass of the Sun, approximately 1.989×10³⁰ kg
These units provide natural scales for physical phenomena and simplify equations in theoretical work.
Regional and Cultural Measurement Systems
Asian Measurement Traditions
Various Asian cultures developed sophisticated weight systems for trade and commerce:
| Unit | Region | Metric Equivalent | Historical Context |
|---|---|---|---|
| Tael | China | 37.5 g | Silver currency, traditional medicine |
| Catty | China/Southeast Asia | 604.78982 g | Market measurements |
| Tola | South Asia | 11.6638038 g | Gold and precious metals |
| Picul | East Asia | 60.478982 kg | Agricultural products |
| Momme | Japan | 3.75 g | Pearls, textiles |
Precious Metals and Gemstones
Specialized weight systems developed for valuing precious materials:
- Troy Ounce: 31.1034768 g, used for gold, silver, and other precious metals
- Pennyweight: 1/20 troy ounce (1.55517384 g), historical coin weight
- Carat: 200 mg (0.2 g), used for gemstones and pearls
The troy system, with its 12-ounce pound, dates back to Roman times and remains essential in precious metals markets worldwide.
Industrial and Agricultural Applications
Large-Scale Measurements
Industry and agriculture require specialized units for bulk materials:
| Unit | System | Metric Equivalent | Application |
|---|---|---|---|
| Quintal | Metric | 100 kg | Agricultural products |
| Short Hundredweight | US | 45.359237 kg | Industrial materials |
| Long Hundredweight | Imperial | 50.80234544 kg | UK industrial use |
| Metric Ton | Metric | 1000 kg | International trade |
Engineering and Construction
Engineering applications often use mixed units depending on regional standards:
- Slug: Imperial mass unit (14.5939029372 kg) used in engineering calculations involving force
- Pound-mass: Used in US engineering alongside pound-force for clarity
- Kilogram-force: Obsolete but historically important in some engineering contexts
Practical Conversion Examples
Everyday Conversions
Cooking Measurements: Converting between grams and ounces for international recipes. 100g of flour equals approximately 3.53 oz.
Postal Services: International shipping requires conversion between pounds and kilograms. A 5 lb package equals 2.268 kg.
Fitness Tracking: Converting between stones/pounds and kilograms for body weight. 11 stone 6 lb equals approximately 72.12 kg.
Scientific and Technical Conversions
Laboratory Work: Converting between micrograms and atomic mass units for chemical measurements. 1 µg equals approximately 6.022×10¹⁷ atomic mass units.
Engineering Calculations: Converting between slugs and kilograms for force calculations in different measurement systems.
International Trade: Converting between metric tons and US tons for commodity pricing and shipping calculations.
Future of Mass Measurement
Quantum Standards
The redefinition of the kilogram in terms of fundamental constants represents a shift toward quantum-based standards that don't rely on physical artifacts. This enables more precise and reproducible measurements worldwide.
Digital Integration
Modern measurement systems increasingly integrate with digital technologies, allowing real-time conversion and data sharing across global networks. Tools like this converter represent the democratization of precise measurement capabilities.
Global Standardization
While traditional units persist in daily use, scientific and technical fields continue moving toward complete metric standardization. Understanding conversion between systems remains essential for international collaboration and commerce.