Translation guide
In Japanese, the word for 'weekday' depends on whether you mean any day of the week, a day that is not a weekend day, or a regular working/school day. The most common and useful term is 平日 (へいじつ), which refers to weekdays as opposed to weekends or holidays.
Referring to a day that is not a Saturday, Sunday, or public holiday, typically a working or school day.
The standard word for 'weekday' in the sense of a non-holiday, non-weekend day. Used in both spoken and written Japanese.
平日は朝早く起きます。
I get up early on weekdays.
この店は平日のみ営業しています。
This shop is open only on weekdays.
Loanword from English, used in some contexts but less common than 平日. Often seen in travel or business contexts.
ウィークデーの料金は安いです。
Weekday rates are cheaper.
Referring to any of the seven days of the week, without distinguishing between weekdays and weekends.
Means 'day of the week'. Used when asking or stating what day it is, e.g., Monday, Tuesday, etc.
今日は何曜日ですか？
What day of the week is it today?
会議は金曜日です。
The meeting is on Friday.
Literally 'week day', but rarely used in modern Japanese. Can mean any day of the week, but 曜日 is much more common.
Emphasizing that a day is ordinary, routine, or not a special occasion.
Means 'ordinary day' or 'usual day'. Used to contrast with special days, not necessarily limited to weekdays.
普段の日は自炊しています。
On ordinary days, I cook for myself.
Literally 'the usual day', implying a typical, uneventful day. Very casual.
今日はいつもの日だね。
Today is just an ordinary day, huh?
If you want to ask 'What day of the week is it?', use 曜日 (ようび), not 平日. 平日 specifically means a non-holiday weekday.
平日 (へいじつ) is the standard word for 'weekday' (Mon-Fri, excluding holidays). 週日 (しゅうじつ) is a rare, formal term that can mean any day of the week, but it's almost never used in conversation.
There are seven days in a week.