In the same way as the 格助詞（かくじょし） (case-marking particle)
と means ‘and’, sometimes it is translated as ‘if’. In these cases, it is considered to be far stronger than
ば,
なら, or
たら (which express hypothetical outcomes). This is because one of the primary uses of
と is highlighting 結果（けっか） ‘a result’. In these cases,
と is actually a 接続助詞（せつぞくじょし）, and shows one of three things.
仮定（かてい）の順接（じゅんせつ） - A result that is assumed to be true, and obvious.
確定（かくてい）の順接（じゅんせつ） - A result that is known to be true.
仮定（かてい）の逆接（ぎゃくせつ） - The opposite of a result that is assumed to be true.
Due to this, the (B) part of a phrase using
と as ‘if’, will always occur when (A) happens, as it is considered to be the result of (A).
-
甘（あま）いものをいっぱい食（た）べると、太（ふと）る。
If you eat a lot of sweet things, you will gain weight.
-
部屋（へや）が汚（きたな）いと、お母（かあ）さんに怒（おこ）られる。
If my room is messy, my mother will yell at me.
-
部屋（へや）が静（しず）かだと、眠（ねむ）れない。
If my room is quiet, I can't sleep.
-
地下鉄（ちかてつ）だと、5分（ふん）早（はや）く着（つ）く。
If it’s the subway, you will arrive 5 minutes faster.
と may not be used in situations where the (B) result ‘might’ happen. It must be definite (or close to definite).
In this particular nuance of
と, despite being translated as ‘if’, the actual meaning is much closer to ‘and’, as
と is expressing that (A) and (B) will always go together.