Ounces are an imperial unit. They are a bit confusing as they can be a volume unit or a mass unit. The metric equivalent would be gram or millilitre.
About 30 gram = 1 oz
About 30 mL = 1 fluid oz
You would typically use fluid ounces (oz) or cups (c) to measure the volume of a mayo jar in customary units.
The usual measurement of weight is Metric, in Grams. You can also use U.S. measurements like Pounds and ounces. Metric system- Gram and Kilogram U.S.- Pounds, ounces, Tons
International avoirdupois ounce -Which is the ounce commonly used in the US to measure weight (or mass) -One ounce is 28.349523125 gramsWhich rounds off to -28.35 gramsIf two decimal places is good enough for what you're doing.
1 ounce is equal to 1/16 pounds. 1 ounce (oz)). = 480 grain; = 28.35 gram; = 0.0075 gallon; = 0.03 quart; = 0.06 pint; = 0.0625 pound; = 0.96 fuid ounce (water). 1 ounce also is equal to 11.34 pennies. 1 ounce is equal to 1/16 pounds. 1 ounce (oz)). = 480 grain; = 28.35 gram; = 0.0075 gallon; = 0.03 quart; = 0.06 pint; = 0.0625 pound; = 0.96 fuid ounce(water). 1 ounce also is equal to 11.34 pennies.
The abbreviation oz for the word ounce or ounces come from the old Italian word onza which meant ounce. The word in modern Italian is oncia.
customary
It is a customary unit.
The opposing systems are imperial and metric, not customary. But, meters are metric.
The pound is NOT a metric unit.
It is customary.
It can be more or less. An once (customary) is bigger than a gram (metric) but a pound (customary) is smaller than a kilogram (metric).
Metric.
Metric
Metric.
It is a customary unit.
A "gran" is a German measurement, it is neither customary or metric. A "gram" is a metric unit.
I'm guessing by customary, you mean imperial. if so inches are customary/imperial