Do you know what weight is, the unit of weight you use every day?

This document categorizes weight units for easy reference:

This is the standard system used globally in science and by the vast majority of countries for everyday use.

Unit Name	Symbol	Conversion to Grams	Notes
Tonne (Metric Ton)	t	1,000,000 g	1 tonne = 1000 kilograms.
Kilogram	kg	1,000 g	The base unit of mass in the SI system.
Gram	g	1 g	The base reference unit for this table.
Milligram	mg	0.001 g	1 gram = 1000 milligrams. Common for medicine and chemicals.
Microgram	μg	0.000001 g	1 milligram = 1000 micrograms. Used in fine-tuned science and pharmacy.
Quintal	q	100,000 g	1 quintal = 100 kilograms. Occasionally used in agriculture.

Primarily used in the United States, and to a lesser extent in the UK, Canada, and other Commonwealth nations.

Unit Name	Symbol	Conversion to Grams	Notes
Long Ton	-	1,016,046.9 g	Primarily used in the UK. 1 long ton = 2240 pounds.
Short Ton	-	907,184.74 g	Primarily used in the US. 1 short ton = 2000 pounds.
Stone	st	6,350.29 g	Commonly used in the UK and Ireland for body weight. 1 stone = 14 pounds.
Pound	lb / lbs	453.59237 g	A crucial unit. This is the exact international Avoirdupois pound definition.
Ounce	oz	28.3495 g	1 pound = 16 ounces. Known as the Avoirdupois Ounce.
Dram	dr	1.7718 g	1 ounce = 16 drams. Not commonly used.
Grain	gr	0.06479891 g	The smallest unit, common to Avoirdupois, Troy, and Apothecaries' systems. 1 pound = 7000 grains.

These units have different standards depending on the region. Pay close attention to the context when using them.

Unit Name	Region	Conversion to Grams	Notes
Jin / Catty (斤)	Mainland China	500 g	The modern market standard. 1 jin = 10 liǎng. Your prompt's "1 jin = 50g" is a misunderstanding of this.
Gongjin (公斤)	Mainland China	1,000 g	Literally "public jin," meaning kilogram. Invented for convenience. 1 gongjin = 2 jin.
Liǎng (两)	Mainland China	50 g	1 jin = 10 liǎng. This is the likely source of the "50g" confusion.
Qián (钱)	Mainland China	5 g	1 liǎng = 10 qián.
Fēn (分)	Mainland China	0.5 g	1 qián = 10 fēn.
Jin / Catty (斤)	Hong Kong, Macau, Taiwan, SE Asia	~604.8 g	Based on the old "Si Ma Jin" (司馬斤). 1 catty = 16 'Si Ma' taels.
Tael / Liǎng (两)	HK, Macau, etc.	~37.8 g	Known as the "Si Ma" tael, where 1 catty (604.8g) = 16 taels. Common in traditional Chinese medicine shops.
Kin (斤)	Japan	600 g	Adopted from older Chinese standards.
Monme (匁)	Japan	3.75 g	Still used in the pearl industry.
Kan (貫)	Japan	3,750 g	1 kan = 1000 monme.
Geun (근)	Korea	600 g	Standard for meat. Can be 400g for vegetables, context is important.

In the modern system used in Mainland China:

It is the Liǎng (两) that equals 50 grams, not the Jin (斤).

This system is used exclusively for weighing gold, silver, platinum, and gemstones.

Unit Name	Symbol	Conversion to Grams	Notes
Troy Pound	lb t	373.24 g	1 troy pound = 12 troy ounces. Not commonly used.
Troy Ounce	oz t / ozt	31.1034768 g	The standard unit for international gold and silver trading. It is heavier than the Avoirdupois ounce (28.35g).
Pennyweight	dwt	1.555 g	1 troy ounce = 20 pennyweights.
Carat	ct	0.2 g	Used exclusively for measuring gemstones like diamonds. 1 gram = 5 carats.
Grain	gr	0.06479891 g	Identical to the Avoirdupois grain.

Unit Name	Symbol	Conversion to Grams	Field / Region
Pound-force	lbf	Not a mass unit	This is a unit of force, not mass. It cannot be directly converted to grams and is a common point of confusion.
Slug	slug	14,593.9 g	A unit of mass in the Imperial system, defined as the mass that accelerates at 1 ft/s² when a force of one pound-force (lbf) is exerted on it.
Apothecaries' Ounce	℥	31.1034768 g	An old pharmaceutical unit, equal in mass to the Troy ounce. Largely replaced by the metric system.
Apothecaries' Dram	ℨ	3.888 g	1 apothecaries' ounce = 8 apothecaries' drams.

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