The world uses for measuring of mass or weight the SI units kilograms or grams. Only three nations have not officially adopted the International System of Units as their primary or sole system of measurement: Liberia, Myanmar and the United States. Scroll down to related links and look at "The not kilogram and gram countries".
Use grams and kilograms when referring to mass in metric units. Don't confuse with weight, Newtons in metric.
kilograms
Kilogram
Grams and kilograms are measurement of weight. For a letter you would use grams. For a package you would use kilograms as it weight is more.
kilograms
kilograms because grams are smaller than kilograms.
grams
kilograms
you can't use kilograms to measure a orange, but you can use grams.
Kilogram
You could (theoretically) use either... However - Kilos is the preferred measurement.
Grams and kilograms are measurement of weight. For a letter you would use grams. For a package you would use kilograms as it weight is more.
kilograms
kilograms because grams are smaller than kilograms.
grams
grams
you should use kilograms
You can use either. If you use kilograms, you will probably get a decimal, less than 1, so grams would be commonly used. By the way, grams and kilograms are units of mass, not of weight.