How to Make a Word Search: Grid Size, Word Count and 7 Steps

To make a word search, pick a theme and a word list, then choose a grid where the words' letters add up to about half the squares: 8 words in a 10×10 grid, 12 in a 12×12, 16 in a 15×15. Write the longest words in first, let words cross where a letter matches, and fill the empty squares with random letters. Then check every line for accidental extra words (a second copy of a short word, or a rude one), and make an answer key.

We tested each step with code, using the generator behind Poozee's Word Search and thousands of random word lists. Here's the method, a worked example built one step at a time, and the numbers behind each piece of advice.

The quick answer: size, directions and word count

These are the three levels of our game. In all three, the words' letters add up to about half of the squares: 51% on Easy, 54% on Medium and 46% on Hard. The rest is filler.

How we tested

We measured two things. First, our game's own puzzles: 600 at each level, 50 for each of its 12 themes. Second, placing word lists the way you would by hand: we drew random lists from the 380 or so words in our themes, wrote them into an empty grid one word at a time in a random spot where each fit, and never moved a word once it was down. We did that with 1,000 lists for every combination of grid size, directions and word count in the tables below.

A word counted as "in the grid" if it could be read in any of the eight directions, because that's how a solver will spot it. Other puzzle makers do things differently, so treat the exact numbers as a guide and the rules of thumb as general.

Step 1: Pick a theme and a word list

A theme makes the list easy to write and gives the puzzle a title. Animals, the ocean, a holiday or this week's spelling words all work. Write down more words than you need, then trim.

• Use words of 3 letters or more, and none longer than the grid is wide.
• Don't hide one word inside another. If the list has both CAT and CATFISH, the solver can find CAT in two places. Check backward too: in our Space list, SUN reads backward inside both URANUS and VENUS, so our generator never puts SUN in the same puzzle as either of them.
• Count the letters. Add up the letters in all your words (leave out spaces and hyphens). That total, not the number of words, decides what size grid you need.

Step 2: Choose the grid size and directions

Here's how many words fit, depending on the grid and the directions you allow. Each number is the most words for which at least 9 in 10 random lists fit on the first try, placed longest first:

Two things stand out. First, the limit is about letters, not words: in every grid, trouble starts once the letters fill roughly three-quarters of the squares. At the across-and-down limits above, the words' letters added up to 75%, 76%, 81% and 86% of the squares, a little more in bigger grids. Our lists averaged about 6 letters a word, so with shorter words you can fit more. Second, allowing more directions barely helps. Diagonal lines are short near the corners, so a long word has fewer places to go than you'd think.

Our game stays at about half the squares, well clear of that limit. One word past it, a lot of lists stop fitting: in a 10×10 grid with words across and down, 12 words fit 90.7% of the time, but 13 words only 77.3%. A puzzle that's three-quarters words is also a weak puzzle, with very little filler to hide them.

Pick the directions for the solver. Across and down only is the right start for young kids. Diagonals, then backward words, make the same list harder without changing how many words fit.

Step 3: Write in the longest words first

Long words are the hardest to fit, so give them the empty grid. For our worked example, an ocean puzzle for young kids, the list is OCTOPUS, DOLPHIN, SHARK, WHALE, CRAB and EEL: 31 letters in an 8×8 grid of 64 squares, a little under half. It runs across and down only.

Of everything we tested, the order made the biggest difference. We took 1,000 random lists of 13 words for a 10×10 grid, across and down (one word more than the limit in the table above), and placed each one three ways:

Same words, same grid: putting the long words in first more than doubled the lists that fit. Short words are easy to tuck into the gaps at the end, while a long word left until last often has nowhere to go.

Step 4: Cross words where the letters match

Every time two words share a letter, you save a square, and the grid has room for more. Look for a letter the next word has in common with one already placed, and run it through that letter.

Four crossings bring the 31 letters down to 27 squares. On the same 13-word lists as above, always crossing when a word could made a real difference:

Crossings also make a better puzzle, because a solver can't skip a letter just because it's already part of a word. In our game's Hard puzzles, crossings save 8.5 squares per grid.

Step 5: Fill the empty squares

Fill every empty square with a random letter. Our game picks filler letters in roughly the mix they have in English, with lots of E, T, A and O and very few Q, X and Z, so the filler looks like the words. On our Easy, Medium and Hard levels, filler ends up as 52%, 50% and 58% of the squares.

Write the filler without looking for words, then check the result, because random letters make mistakes:

Step 6: Check for extra copies and rude words

It's tempting to skip this step, but our numbers say it's not optional. We kept the words of all 1,800 of our game's puzzles where they were and filled the empty squares again with fresh random letters:

Short words cause almost all the extra copies. On Hard, 17.4% of three-letter words could be read twice, but only 1.5% of four-letter words and 2 of 8,174 longer ones. So look for every three- and four-letter word on your list, in all eight directions, even if your puzzle only runs across and down. A kid will circle a backward EEL just as happily.

Rude words are the bigger surprise. The block list our game uses has 22 swear words, slurs and other words you don't want on a classroom handout, and on a 15×15 grid, random filler spelled one of them more than half the time. On Hard, 86% of them were only three letters long, which is exactly why they're so easy to make by accident. Read every row, column and diagonal of filler, both ways, before you photocopy.

When you find a problem, change one filler letter and check that spot again. In the example, the accidental EEL starts on the sixth letter of the bottom row, and changing that E to an A fixes it.

What about the filler letters themselves? We tried two other mixes on the same Hard grids. Using every letter of the alphabet equally often cut the grids with a word twice to 6.2%, and with a blocked word to 33.3%, but didn't remove them. Using only letters from your word list, so the filler looks even more like the words, made extra copies more common: 16.8% of grids. Whatever you choose, you still have to check.

Our generator does this check every time: it reads every line both ways and throws the filler out if a listed word appears more than once or a blocked word appears at all, then tries new filler. 56.3% of our Hard puzzles needed more than one try before they passed (21.7% on Easy, 35.8% on Medium). It checks the words on their own too, before any filler goes in: two words placed end to end can spell a blocked word or a second copy between them, and no filler can fix that, so it places the list again instead.

Step 7: Make an answer key

Copy the finished grid and mark every word on it, or keep the copy you circled while checking. The answer key is also your last check: if you can't find a word in one clean, straight line, the solver can't either.

Tips for teachers and parents

• Graph paper and a pencil make this much easier. Write the words in first and the filler last, so you can still move a word if the list won't fit.
• Write the words in capitals, one letter per square. Lowercase letters are easier to read as other letters (b and d, for example).
• List the words in alphabetical order under the grid, so solvers can find a word on the list and cross it off quickly.
• Use the list to practice spelling. A solver has to match every letter, so a word search is a natural way to review a week's words.
• Don't need your own list? Our Word Search makes a fresh puzzle on 12 themes at the three levels above, with every check already done, and its Print button gives you a clean page with just the grid and the word list.

Once the puzzles are made, our word search tips show solvers how to find words faster, from hunting the rarest letter to reading backward.

Keep playing

• Play Word Search: 12 themes on three levels, ready to play or print
• Word search tips: how to find words faster, measured on 1,800 grids
• How to make a nonogram: design your own picture logic puzzle, with a check for one solution
• Word Guess, a daily five-letter word puzzle