字幕翻譯和其他類型翻譯(如,口譯、書籍翻譯…等)最明顯的差異是,字幕翻譯必須掌握每行字幕與角色說話的時間長度,讓兩者盡可能同步,才不會讓觀眾分心或是無法理解原意;因此每一行字幕翻譯都需精確、翻譯口吻與角色一致,才有辦法讓觀眾在字幕閃現的短短幾秒鐘,快速看懂內容。由於你我在幾秒內可以看完的字數有限,通常是14個字左右,(在歐洲,甚至規定每兩行字幕都要停留六秒(Gottlieb, 1992, pp. 164-165))所以每一字幕翻譯出現的長度都會落在這個範圍,不過實際呈現方式就會依照各家電視台或是影音播放平台的字幕稿件規範而有些微差異。
-I know you're an Army doctor and you've been invalided home from Afghanistan. (我知道你是軍醫//因傷從阿富汗退役)
-You've got a brother worried about you, but you won't go to him for help(你有個哥哥很擔心你//但你不想向他求助)
-because you don't approve of him, possibly because he's an alcoholic, more likely because he recently walked out on his wife.(你對他不滿,可能是因為他酗酒//更有可能是他剛甩掉他老婆)
-And I know your therapist thinks your limp's psychosomatic. (我還知道你的心理醫生認為//你跛腳是心理因素)
-Quite correctly, I'm afraid. (這個診斷恐怕是對的)
-That's enough to be going on with, don't you think? (這些應該就夠了,不是嗎?)