Translation guide
Expressing 'half the amount' in Japanese depends on what is being halved: a quantity, a price, a portion, or a comparative degree. The most common pattern uses 半分 (はんぶん) with the particle の or as a standalone noun. For countable items, 半数 (はんすう) is used. In comparative contexts, 半分の～ or ～の半分 is natural.
Expressing that something is half of a whole amount, size, or portion.
The most common and versatile word for 'half'. Can be used as a noun or with の to modify another noun.
Please cut the cake in half.
Half of this amount is enough.
Pattern to say 'half of something'. Place the thing being halved before の半分.
I save half of my salary.
Specifically means 'half price'. Used in commercial contexts.
This item is half price.
Means 'half the number' for countable things like people or items.
Half of the participants were women.
Expressing that something is half as much in degree, intensity, or comparison.
Used to say 'half the (noun)' where the noun is an abstract quantity like size, length, or effort.
I finished it in half the time.
I got the same result with half the effort.
Pattern for 'half the (noun) of (something)'. More explicit comparison.
Specifically referring to a monetary amount being halved.
Use 半分 for uncountable amounts, portions, or abstract halves. Use 半数 for countable numbers of people or things.
I drank half of the water.
Half of the students were absent.
English 'half the amount' often translates simply as 半分. Adding 量 (りょう) is usually unnecessary and can sound unnatural unless emphasizing a measured quantity.
This box is half the size of that box.
I bought this for half the price.