Lesson 1 of 8
Square colors: light or dark in one second
The foundation of every blindfold skill. One rule that never fails, plus shortcuts to make it instant.
Practise it now, free
The problem to solve
Eyes closed, in under one second: is f7 light or dark? Which color does the bishop on c1 live on? This is THE building block of blindfold chess. As long as it is not automatic, following a game in your head keeps stalling.
Good news: this is the easiest visualization skill to automate, because there is a binary rule that never fails, plus visual shortcuts that make it even faster. Learn the rule first, then the shortcuts.
The core: the parity rule (never fails)
Convert the file to a number: a=1, b=2, c=3, d=4, e=5, f=6, g=7, h=8. Every square now has two numbers, the file and the rank, each either even or odd.
The parity rule
Same parities (both even OR both odd) = DARK square. Different parities (one even, one odd) = LIGHT square.
- a1: file 1 (odd), rank 1 (odd). Same parities, so dark. (a1 is indeed dark.)
- h1: file 8 (even), rank 1 (odd). Different, so light.
- f6: file 6 (even), rank 6 (even). Same, so dark.
- e4: file 5 (odd), rank 4 (even). Different, so light.
Same rule, sum formulation: add file + rank. Even sum = dark, odd sum = light. f6 is 6+6 = 12, even, dark. h1 is 8+1 = 9, odd, light. It is exactly the same thing (two same parities always make an even sum). Keep whichever phrasing sticks: compare, or add.
To anchor it, picture two light switches, one for the file and one for the rank, each either up (even) or down (odd). Both switches in the same position: light off, square dark. Switches in different positions: light on, square light. This image kills the classic confusion: it is not "even = dark", it is the COMPARISON of the two parities that decides.
Shortcut 1: low letters, high letters
The two rows, if you prefer patterns to arithmetic
On an odd rank (1, 3, 5, 7) the dark squares are a, c, e, g. On an even rank they are b, d, f, h. Two rows to hold, and you never convert a letter into a number again: f7 is an odd rank, and f is not in a-c-e-g, so f7 is light.
The only slow part of the rule is converting the letter to a number. Remove it with a visual shortcut: the letters a c e g are "low" (no ascending stroke) and they are the odd files. The letters b d f h are "high" (one vertical stroke) and they are the even files. Mnemonic: "ACE-G", the aces are the odd ones.
You read the file parity at a glance, no counting. Combine with the rank (the digit is already there): low (odd) letter + odd rank, same parities, dark. High (even) letter + odd rank, different, light. For most players this is the fastest method in practice.
Shortcut 2: anchor squares and alternation
Instead of computing, start from a known reference square and walk from it. Memorize these anchors once and for all:
- a1 is DARK (bottom-left corner from White's side).
- h1 is LIGHT: "white on the right", the board orientation rule.
- The long diagonal a1-h8 is entirely DARK.
- The long diagonal a8-h1 is entirely LIGHT.
- The queen starts on her own color: white queen on d1, a light square; black queen on d8, a dark square.
The movement rule
A diagonal neighbor keeps the SAME color. An orthogonal neighbor (side by side, or above/below) flips to the OPPOSITE color.
Example
I know d1 is light (white queen). d2 is orthogonal from d1, so dark. e2 is diagonal from d1, so light.
Slower than the math, but excellent for double-checking a result, and for beginners who dislike numbers.
Shortcut 3: pure memorization (the end goal)
Advanced players end up KNOWING the color without any calculation, the way you know your multiplication tables. You start with the rule (parities + low/high letters), and through drilling you finish by not computing at all. The rule is temporary scaffolding: drill until the answer is a reflex, then the scaffolding falls away on its own.
Why it matters
Its real job: a checksum
In a blindfold game the colors are how you catch yourself drifting. If your light-squared bishop lands on a dark square, or a knight comes back to the color it left, the position in your head is already wrong. Stop and rebuild rather than play on.
- The bishop filter: a bishop never leaves its color. Seeing the color instantly tells you whether a bishop can ever reach a square (see the bishop lesson).
- Good bishop / bad bishop, weak squares around the king, color complexes.
- All of blindfold visualization: following a game in your head without getting lost.
Try it: the live board
Hover or tap a square to watch the trick compute itself. Switch on blind mode to train for real, and chase a long streak in the quiz.
Recommended training progression
- Learn the rule: same parities = dark. Test 10 squares calmly.
- Add the letter shortcut (low/high) to remove the conversion step.
- Timed quiz: call light or dark on random squares, aim for a long streak.
- Blind mode: neutral board, guess before revealing.
- Cross-check with anchors: verify answers via the queens and the long diagonals.
In-app drill
Train this daily in /train/square-colors. It is the foundation: every other lesson leans on it.
Common mistakes
- Confusing "even = dark" with the real rule. It is not the parity of one number, it is the COMPARISON of both parities (or the parity of the SUM). a8: file 1 is odd, yet the square is light, because rank 8 is even (different parities).
- Forgetting the orientation. Without "white on the right" you can mirror the whole board in your head. Always anchor h1 = light.
- Calculating forever. The goal is the reflex, not lifelong arithmetic. Drill until the rule disappears.
- Swapping the movement rule. The DIAGONAL keeps the color; the orthogonal step flips it.