How do you tell if a square is light or dark?

How do you determine whether a square is light or dark? Do you visualize the whole board, or do you rely on a rule like knowing h1 is light and then calculating from there?

1. Another way is to ask odd or even looking at files a,c,e,&g as also being odd.

   • Odd file a,c,e,g + odd numbered rank 1,3,57 = dark (ie 1a, 3g, 7c...)
   • Odd file Odd rank. = Dark
   • Odd file Even rank = Light
   • Likewise: Even file Odd rank = Light
   • Even file Even rank = Dark
   • Both same = Dark
   • Different = Light

2. There was a recent post with a link to an article about chess and aphantasia (?). It basically gave your method, plus noting that the odd-numbered files are those whose letter appears in the word CAGE.

3. If the square is even, it's most likely light while odd squares are dark.

4. Boards for the blind I have found out have slightly raised tiles for one color. Often they have peg holes and pegs at the bottom of each piece. They also have pegs at the tops of one color. Those boards are for the completely blind.

5. One way if you don’t know it by heart or aren’t a very strong player is, at least for some squares, is to remember which bishop ends up on a particular square in openings. For example, g5 is a dark square because that’s where white’s dark squared bishop goes to pin the knight in many positions. f5 is a light square (think of the Caro-kann). b5 and c4 are light squares (Spanish and Italian).

6. When solving blindfold puzzles I tend to have good visualization of only about a quarter of the board at any moment, scanning around and reconstructing as needed. Knowing light/dark squares is mostly automatic, but if I haven't practiced the skill much and it's rusty, I may need to think about it to be sure.

7. Just ask the bishops and they will tell you. :)