How many blocks do you have to fall down to die in minecraft?

Well, honey, in minecraft, a player will start taking fall damage if they fall from a height of 4 blocks or higher. If a player falls from a height of 23 blocks or more, they will die upon impact. So, to answer your question, you have to fall down at least 23 blocks to meet your untimely demise in the pixelated world of Minecraft.