A timescale is the length of time something takes, or is planned to take, from beginning to end. If a boss asks 'What's the timescale for this project?', they are asking how long it will take and by when it will be done. It is a countable noun: a short timescale, a tight timescale, a realistic timescale, within the timescale we agreed.

A timescale is the length of timetimescale指的是所花的時間長度 something takes, or is planned to take某件事實際花的，或預計要花的 from beginning to end從開始到結束If a boss asks 'What's the timescale for this project?'如果老闆問'What's the timescale for this project?'（這個專案的時程是多久？） they are asking how long it will take and by when it will be done他其實是在問要花多久、什麼時候能完成It is a countable noun這是個可數名詞 a short timescale, a tight timescale, a realistic timescale像a short timescale（短時程）、a tight timescale（緊迫的時程）、a realistic timescale（合理的時程） within the timescale we agreed在我們談好的時程之內

There is a second, larger use in science and history: geological timescales, the timescale of evolution — here it means the whole stretch of time over which something happens, often unimaginably long.

There is a second, larger use in science and history在科學和歷史領域還有第二種、範圍更大的用法 geological timescales, the timescale of evolution像geological timescales（地質時間尺度）、the timescale of evolution（演化的時間尺度） here it means the whole stretch of time over which something happens這裡指的是某件事發生所橫跨的整段時間 often unimaginably long常常長得難以想像

Two practical notes. It is much more common in British English than American, where people usually say timeline, time frame or schedule; and although timescale and timeline get mixed up, they are not the same. A timescale is the duration, an amount of time; a timeline is the sequence, what happens when, often drawn as a line with dates on it.

Two practical notes兩個實用的提醒It is much more common in British English than American這個詞在英式英語比美式常見得多 where people usually say timeline, time frame or schedule美式英語通常會說timeline、time frame或schedule and although timescale and timeline get mixed up雖然timescale和timeline常被搞混 they are not the same但它們並不是同一回事A timescale is the duration, an amount of timetimescale是持續多久、一段時間的量 a timeline is the sequence, what happens when而timeline是順序，也就是什麼時候發生什麼事 often drawn as a line with dates on it常常畫成一條標著日期的線

British writers use both spellings, timescale and time scale, with the single word now more usual.

British writers use both spellings, timescale and time scale英國作者兩種拼法都用，timescale和time scale都有 with the single word now more usual不過現在合寫成一個字比較常見