The mass units in the converter:
"carat (ct), centigram, decigram, dekagram, dram, grain, gram (g), hectogram (hg), hundredweight, kilogram (kg), kiloton, megagram, megatonne, microgram, milligram (mg), nanogram, ounce (oz), petagram, picogram, pound (lb), quarter, stone (st) and ton"
To convert only the common mass units, please check weight converter page.
Metric Mass Units
The base unit of mass in the metric system is kilogram. Here is a quick reference list for the base metric mass unit, kilogram:
- 1 kilogram = 1000 grams
- 1 kilogram = 2.20462 pounds
- 1 kilogram = 35.274 ounces
- 1 kilogram = 0.157 stone
- 1 kilogram = 1⁄1000 metric ton
Kilogram Definition (Before May 2019):
Kilogram is equal to the mass of the international prototype (platinum-iridium cylinder kept in France) of the kilogram. The kilogram prototype is also known as "Le Grand K".
Kilogram Redefinition (After May 2019):
On 16 November 2018, for the most accurate measurement, the scientists agreed that the SI base unit definitions should not be based on the physical objects but instead based on fundamental constants of nature that does not change over time, such as Planck constant etc.
With the new definition, the Kibble balance will be used to measure the mass of the kilogram. When you place a weight on the Kibble balance, the machine produces an electric current proportional to Planck’s constant. With Planck’s constant set, the kilogram will correspond to a specific amount of current in the Kibble balance.
Based on this, the redefinition of kilogram is:
"Kilogram is defined by taking the fixed numerical value of the Planck constant h to be 6.62607015×10−34 when expressed in the unit J⋅s, which is equal to kg⋅m2⋅s−1, where the metre and the second are defined in terms of c and ΔνCs."
With the new definition, the kilogram also depends on the definitions of the second and the metre.
Imperial and US Customary Mass Units
In the imperial and the US Customary system the fundamental unit of mass is pound (lb). All other units are either the fractions or the multiples of pound.
Here is the list of the Imperial and the US Customary mass units:
- grain (gr) = 1⁄7000 pound
- drachm (dr) = 1⁄256 pound
- ounce (oz) = 1⁄16 pound
- pound (lb)
- stone (st) = 14 pounds
- quarter (qtr) = 28 pounds
- hundredweight (cwt) = 112 pounds in imperial, 100 pounds in US Customary
- ton (t) = 2240 pounds in imperial, 2000 pounds in US Customary