Convert between 20 weight units instantly — metric, imperial and scientific. From milligrams to solar masses, with real-time results.
The kilogram is the SI base unit of mass, redefined in 2019 by fixing Planck's constant. In everyday usage, kilograms and grams dominate most of the world, while the United States and United Kingdom rely on pounds and ounces for body weight and food. The International System of Units treats mass as a base quantity, with weight being the gravitational force on that mass.
This converter supports 20 units spanning over 60 orders of magnitude — from the electron mass (~9.1 × 10⁻³¹ kg) to the solar mass (~1.989 × 10³⁰ kg). Imperial units (grain, drachm, ounce, pound, stone, short ton, long ton) are linked by exact definitions. Scientific units like the atomic mass unit (u) are defined by fundamental constants.
All weight conversions are linear. Each unit has a fixed factor f (kilograms per unit). The general formula is:
Universal linear formula:
Where f_source is the number of kilograms in one source unit, and f_target is the number of kilograms in one target unit. The converter first converts to kilograms, then to the target unit.
An average adult weighs about 70 kg = 154.3 lb = 11 stone = 2,469 oz. In atomic terms, 70 kg ≈ 4.22 × 10²⁸ u — illustrating the vast scale gap between everyday and atomic masses.
400 troy oz = 12.441 kg = 27.43 lb. Troy ounces (31.10 g) are heavier than avoirdupois ounces (28.35 g), which is why gold is always priced in troy oz on international markets.
Up to 150 metric tons = 150,000 kg = 330,693 lb. This equals ~2.51 × 10⁻²³ times the Earth's mass — a vivid illustration of just how massive planetary bodies are compared to biological life.
Proton: 1.6726 × 10⁻²⁷ kg; Electron: 9.1094 × 10⁻³¹ kg. The proton is 1,836 times heavier — a fundamental constant of atomic physics determined through precision spectroscopy.
Enter the numeric weight value in the input field at the top.
Select the source unit from the dropdown — all 20 units are available.
The value is converted to kilograms using the exact conversion factor.
From kilograms, the result is converted to every other unit simultaneously.
Results update instantly as you type; key units appear in the top grid and full groups are in expandable sections.
1 kg ≈ 2.2046 lb — multiply kg × 2.2 for a quick pounds estimate.
1 stone = 14 lb, widely used for body weight in the UK and Ireland.
Troy ounce ≠ avoirdupois ounce: oz t = 31.10 g vs oz = 28.35 g.
The atomic mass unit (u) ≈ 1.66054 × 10⁻²⁷ kg (1/12 of carbon-12 atom).
Metric ton = 1,000 kg; US short ton ≈ 907 kg; UK long ton ≈ 1,016 kg.
Mass is the amount of matter in an object (measured in kg), while weight is the gravitational force acting on that mass (measured in newtons). On the Moon, an object has the same mass but weighs about 1/6 as much as on Earth.
There are approximately 2.20462 pounds in 1 kilogram. The exact definition is 1 lb = 0.45359237 kg, internationally agreed in 1959. Quick shortcut: multiply kg by 2.2.
A troy ounce equals 31.1035 g, compared to 28.3495 g for an avoirdupois ounce. The troy system originated in medieval Troyes, France. Gold, silver and platinum are priced in troy ounces globally, a centuries-old trading convention.
The unified atomic mass unit (u), or dalton (Da), equals 1/12 the mass of a carbon-12 atom: approximately 1.66054 × 10⁻²⁷ kg. It is the standard unit for atomic and molecular masses in chemistry and physics.
Since 20 May 2019, the kilogram is defined by fixing Planck's constant to exactly 6.62607015 × 10⁻³⁴ J·s. This replaced the old platinum-iridium cylinder in Paris, making the kilogram infinitely reproducible anywhere in the universe.
The metric ton (1,000 kg), US short ton (~907 kg) and UK long ton (~1,016 kg) evolved from different national systems. The metric ton is standard in science and international trade; always specify which ton you mean in contracts.
All conversion factors follow BIPM/NIST international standards. Particle masses use CODATA 2018 values. Astronomical masses use IAU 2012 nominal values.