It depends on contexts. ✕あらかじめ予約してください(guidance) ★予means「あらかじめ」 △前もって予約してください(guidance,conversation) 〇事前に予約してください(guidance,formal) -------------------- 〇あらかじめ卵を白身と黄身に分けておきます(recipe,document) △前もって卵を白身と黄身に分けておきます(recipe,conversation) ✕事前に卵を白身と黄身に分けておきます(recipe) -------------------- 〇あらかじめ調べてあります(conversation) 〇前もって調べてあります(conversation) 〇事前に調べてあります(conversation,document,formal) -------------------- 〇あらかじめ想定済みでした(explanation,conversation)→★予想 ✕前もって想定済みでした(explanation) 〇事前に想定済みでした(explanation,formal) -------------------- 〇あらかじめ知っていました(conversation) 〇前もって知っていました(conversation) 〇事前に知っていました(conversation,document,formal) ★For more information For example, I made this list by googling "あらかじめ＋verb". You can search あらかじめ in コロケーション辞書. (1)コロケーション辞書テストページ https://collocation.hyogen.info/ (2)goo https://dictionary.goo.ne.jp/clj/

Penso che gli avverbi あ ら か じ め, 前 も っ て e 事前 に vogliono dire lo stesso. Sono sempre intercambiabili al 99%. - - - - - - - - I respect Ayumi-san's answer but I have a different opinion from a different angle. It is only a difference of opinion. I think the adverbs あらかじめ, 前もって, and 事前に means all the same. They are 99% always interchangeable. The difference in usage of these words is, after all, a matter of rhetoric. Sorry, Ayumi-san, let me use your sentence. The following is my opinion 〇あらかじめ予約してください （▲ 予め予約してください） 〇前もって予約してください 〇事前に予約してください 〇あらかじめ卵を白身と黄身に分けておきます 〇前もって卵を白身と黄身に分けておきます 〇事前に卵を白身と黄身に分けておきます 〇あらかじめ調べてあります 〇前もって調べてあります 〇事前に調べてあります 〇あらかじめ想定しておく。 〇前もって想定しておく。 〇事前に想定しておく。 〇あらかじめ知っていました 〇前もって知っていました 〇事前に知っていました - I checked all the sentences with "OK", which means I think all the sentences are grammatical and make sense. In other words, I don't care if it is a good writting or not, only care if it is grammatical and making sense or not - あらかじめ and 前もって are genuine Japanese word(訓読み). 事前(に) is a word consisted of Kanji（音読み）. That is why 事前に look like formal. - You can say あらかじめ予約する is incorrect (or redundant) because, when you make "a reservation", it is always "in advance（あらかじめ）"; you never make a reservation a posteriori; so you don't have to say "in advance（あらかじめ）"; it is redundant. Yes, it is redundant but I think it is allowed as a kind of emphasis. If you insist you never allow redundancy, you shouldn't allow "前もって予約する“ nor "事前に予約する“ either. - 予め（あらかじめ）予約する is, although grammatical, looks like really redudant．So it is better to write あらかじめ予約する . It is only a difference of how you write. - I think あらかじめ is least used among the three. It is probably because あらかじめ was first used to read Chinese documents in Japanese 1500 years ago, like 予 と書いて あらかじめ と読む、or 須 と書いて、すべからく と読む．It is rather a big word. P.S: if you want to pass some examination of Japanese, I recommend you should follow Ayumi-san's opinion.

As you may know. Here is a page with the same question on another site. https://oshiete.goo.ne.jp/qa/8569542.html Here is a page of the topic "予め予約" on another site. https://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q1374270298 In my opinion, 前もって想定 sounds strange because this 想定 looks like assumption（証拠のない）/supposition, it isn't a volitional thing like 予約. 前もって = in advance あらかじめ also means "in advance", but あらかじめ想定済みでした's 想定(予想) is different from 前もって想定済みでした's 想定. In my opinion, for cooking, あらかじめ/前もって/事前に mean different length of time, and あらかじめ sounds better for food preparation, especially this case, but actual usages seem to be the same(I googled some recipe). Actually, I think that all of the sentences are usable.