also: づつ
Attaches to a quantity or number to indicate an equal distribution per person, item, or unit.
一人に二つずつクッキーをあげた。
I gave two cookies to each person.
at a time; in portions
Indicates doing something in repeated small amounts or stages, often with a sense of gradual progression.
少しずつ日本語が上手になっている。
My Japanese is getting better little by little.
I handed out the apples three at a time.
このノートは一冊百円ずつです。
These notebooks are 100 yen each.
毎日三ページずつ読むことにしている。
I make it a rule to read three pages at a time every day.
少しずつ日本語が上手になってきた。
My Japanese has been improving little by little.
Please call out the names one at a time.
I'm reading five pages of the book each day, bit by bit.
ごとに means 'every' or 'at each interval' and highlights repetition across units, while ずつ highlights an equal amount given to or done by each unit.
Standard kana spelling; the kanji 宛 is rarely used.
Alternate kana spelling, historically used but now less common than ずつ.
Rare kanji form; learners should use kana.
Modern ずつ is the standard spelling of earlier づつ, a distributive particle already found in classical Japanese; its deeper origin is uncertain.