Board games in the crossword-tile family print special squares that boost the value of a play. There are two families: squares that boost a single letter, and squares that boost the whole word. Knowing precisely how each behaves is the difference between a good turn and a great one.

Double-letter square

A double-letter square doubles the value of the single tile placed on it, and nothing else. It applies at the moment the tile is placed and only for that turn. Because it acts on one tile, it pays off most when you cover it with a heavy letter such as J, Q, X, or Z rather than a one-point vowel.

Triple-letter square

A triple-letter square triples the value of the tile placed on it. The same logic applies, only more so: a triple-letter square under a ten-point tile contributes thirty points before any word multiplier is considered. Steering a rare tile onto a triple-letter square is one of the most reliable ways to lift a modest word into a strong score.

Double-word square

A double-word square multiplies the value of the entire word by two, after every letter multiplier has been applied. It rewards length, because it acts on the sum of all the tiles. A long, balanced word across a double-word square often outscores a short word built around a single premium tile.

Triple-word square

A triple-word square multiplies the whole word by three. These are the most powerful single squares on the board and are usually placed near the edges. Reaching one with a long word, or with a rare tile elsewhere in the same word, produces the highest scores in ordinary play.

When more than one multiplier applies

A single play can cover several premium squares at once. Letter multipliers each affect their own tile; word multipliers each affect the whole word and are applied one after another. A word that covers two double-word squares is multiplied by four overall; a double-word and a triple-word together multiply it by six. This stacking is the source of the largest scores in the game. The exact arithmetic is shown in How Word Scoring Works.

Common scoring mistakes

Re-counting a used premium square. A premium square only rewards the turn a tile is first placed on it. Playing through it later scores it at face value.
Applying a word multiplier before letter multipliers. Letter multipliers always come first; the word multiplier acts on the total afterward.
Wasting a triple-letter square on a vowel. Tripling a one-point tile adds only two points. Save high-value letter squares for heavy tiles.
Forgetting the seven-tile bonus. Using all seven tiles adds 50 points, which frequently outweighs a single premium square.
Assuming blanks earn points on premium squares. A blank is worth zero even on a letter multiplier, though word multipliers still apply to the rest of the word.

Try placing premium squares under different tiles in the optimizer to see how the ranking changes, and read the strategy guide for how to plan around them.