American-style crossword grids follow five core rules: 180° rotational symmetry, no unchecked squares, no words under three letters, every white square connected in one region, and black squares used sparingly. Typical size is 15×15 (daily) or 21×21 (Sunday). The New York Times caps word count at 78 for a themed 15×15, 72 for a themeless 15×15, and 140 for a 21×21, per its submission guidelines.
What symmetry does a crossword grid need?
Standard grids use 180° rotational symmetry: if you rotate the grid half a turn, the pattern of black squares is unchanged. A black square at row 2, column 5 of a 15×15 grid requires a matching black square at row 14, column 11.
Other symmetry types exist, and constructors use them for specific puzzles:
| Symmetry | What it means | Typical use |
|---|---|---|
| 180° rotational | Same after a half turn | Standard American crosswords |
| 90° rotational | Same after a quarter turn | Decorative or specialty puzzles |
| Mirror (left-right or top-bottom) | Reflection across an axis | Uncommon in American style, common in some other traditions |
| Diagonal | Reflection across a diagonal | Rare |
| None (asymmetric) | No pattern requirement | Some themed or freestyle puzzles |
If you're submitting to a mainstream American outlet, use 180° rotational symmetry unless the outlet says otherwise. In Gridsmith, 180° rotational symmetry is applied automatically when you place blocks, and the symmetry tool is in the Tools menu.
How many black squares and words should a grid have?
The binding limits are word-count maximums, not block counts. Fewer words means fewer blocks and longer answers.
| Puzzle | Grid | NYT word-count maximum |
|---|---|---|
| Themed daily | 15×15 | 78 |
| Themeless | 15×15 | 72 |
| Sunday | 21×21 | 140 |
These figures come from the NYT submission guidelines. The guidelines allow the editor to accept slight overages when a theme calls for it. Other outlets set their own limits, so check each venue's published specs rather than assuming the NYT numbers apply.
Block counts aren't fixed by rule. They follow from the word count and the layout, and a common stylistic goal is to keep blocks to a modest share of the grid so the fill stays strong. Gridsmith's live stats show your word count, block count, and block percentage while you edit.
Why word count matters: a 15×15 grid has 225 squares. Each extra block cuts a long answer in two and usually adds words, which makes the fill easier but the puzzle choppier. Themeless puzzles run lower, which is why they demand stronger fill.
What is an unchecked square?
An unchecked square is a white square that belongs to only one answer (across or down), not both. Most American outlets, including the NYT, don't allow them. Every letter should be "checked" by a crossing word, so a solver can always use a crossing to confirm a guess.
Gridsmith reports the number of unchecked squares in its live stats. Some British-style and cryptic grids deliberately leave alternate squares unchecked, but that is a different tradition from the American style, and Gridsmith does not support barred or cryptic grids.
What is a cheater square?
A cheater square (or "helper square") is a black square that doesn't change the word count. Because it sits next to an existing block or at a position where the added block doesn't split a word into extra entries, it makes the fill easier without raising the number of answers. Constructors add them to rescue a hard corner without breaking the word-count cap.
A plain example: a black square at the end of an entry shortens that word by one letter and splits nothing, so the total number of entries stays the same. Because the symmetric partner also changes, check that the paired change is also count-neutral. Overusing cheaters is seen as a weakness, so use them sparingly.
What does "connected" mean in a crossword grid?
Connectivity (also called interlock) means every white square can be reached from every other white square by moving through adjacent white squares, without crossing a black square. A grid with an isolated island of white squares, or one split into two regions by a diagonal wall of blocks, fails this rule.
To check: pick any white square and imagine flooding outward across white neighbors. If every white square fills, the grid is connected.
What is the minimum word length?
Three letters. Two-letter entries are not accepted in standard American grids. Some small formats, such as certain minis, may relax this, so check the target outlet.
Do the rules differ between daily, themeless, and Sunday grids?
The structural rules are the same: symmetry, no unchecked squares, three-letter minimum, connectivity. What changes is size and word count.
- 15×15 daily (themed): up to 78 words (NYT). Theme answers take the longest slots.
- 15×15 themeless: up to 72 words (NYT). No theme, so more open space and longer entries.
- 21×21 Sunday: up to 140 words (NYT). More theme entries and longer ones.
For the full NYT conventions, read how to make an NYT-style crossword. For step-by-step construction, see how to make a crossword puzzle. Rule terms are defined in the glossary.
Frequently asked questions
What is the maximum word count for a 15×15 crossword?
For the NYT, it is 78 words for a themed puzzle and 72 for a themeless, per its submission guidelines. Other outlets set their own limits.
Do crossword grids have to be symmetrical?
For standard American-style puzzles, yes: 180° rotational symmetry is the norm and most outlets expect it.
How many black squares should a 15×15 crossword have?
There is no single required number. Block count follows from your word-count target and layout, so manage word count first and let the blocks fall out of that.
What is a cheater square?
A black square that doesn't increase the number of words in the grid. Constructors use it to ease a tough area of fill without breaking the word-count cap.
Can a crossword have unchecked squares?
Not in standard American grids. Every white square must be part of both an across and a down answer.