How is damage reduction from armor calculated?

I'm late game and now my Armor is stupid high (I'm at 60+, I think).

Early game things do no more than a quarter heart, but late game bosses still hit me pretty hard.

So how is the damage from the armor calculated? If something was supposed to do me 10 hearts damage when I'm in my shorts, how much will I take with 10/20/30/40/50 armor?

According to this Reddit Post ,

Each additional armor point reduces incoming damage by 1/4 heart

(To a minimum of 1/4)

Furthermore

Additionally, for defense elixirs and per-strike damage:

Level 1 defense reduces damage by 1 heart (4 armor). Level 2 defense reduces damage by 3 hearts (12 armor). Level 3 defense reduces damage by 6 hearts (24 armor).