How to say "practically" in Japanese

• ほとんどJLPT N4approx.Common
  adverbCovers 'practically' in its sense of 'almost, nearly': practically everyone, practically every day. The common choice when the meaning is 'very nearly but not quite'.
  夕食ゆうしょくの準備じゅんびはほとんどできています。↗

  The dinner is almost ready.
• と言っていいほどといっていいほど
  expressionCovers 'practically' as in 'so much that one could even say': something is so close to being X that calling it X is fair. An emphatic phrase, and a less common choice.
• 実際にじっさいに
  adverbCovers 'practically' meaning 'in practice, in actual fact' — what really happens rather than what is planned. It does not mean 'almost'; for 'practically everyone' it is not the word.
  実際じっさいにうまくいかなければ理論りろんは全まったく役やくに立たたない。↗

  Theory is quite useless unless it works in practice.

Choose 「ほとんど」 for 'practically' meaning 'almost, nearly'; 「と言っていいほど」 when something is so extreme you could call it that; 「実際に」 for 'practically' as 'in practice' rather than in theory.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• ほとんどalmost
• と言っていいほどといっていいほどso much that one could even say
• 実質じっしつin essence
• 実際にじっさいにin practice