The Spache formula is a readability measure which estimates an elementary reading grade level. Find out how it's calculated and how you can best use it. 

What is a Spache score?

Spache is a readability test for English. It is best for texts up to fourth-grade level. For grading texts aimed at older children, the Dale-Chall test is more suitable.

As it is such a specialist tool meant for a specific age group, it is not really suitable for general readability use. Whether you’re a teacher or a budding children’s author, you can use our tool to keep your young readers’ best interests.

Where did the test come from?

Spache was introduced by George Spache in 1952 in The Elementary School Journal. It’s a word-list style of formula. It compares the words in a text to a set list of everyday words, which someone up to fourth grade generally can understand.

The formula was introduced by Spache in a journal article named ‘A New Readability Formula for Primary-Grade Reading Materials.’

He created the formula in response to many previous frameworks being formulated for adults. Spache saw a neglected age group which needed to be accounted for. He notes in the paper that there are other frameworks providing this solution, but they were too complicated.

How does the Spache test work?

The variables in Spache’s formula are:

  • Sentence length
  • Unfamiliar or difficult words

The formula is calculated as follows:

Spache formula | Readable, free readability test

For your reference, here is the revised Spache word list. These are measured against the words used in the text in question. This allows for analysis of familiar versus unfamiliar words. Initially, the formula collected data from a sample of 100-150 words. For a longer text, this would have been hard to calculate. Now, we can now automate the calculation. Readable analyses based on the entire text.

The calculation is a grade level based on:

  • ASL - average sentence length.
  • PDW - the percentage of difficult words.

After the original word list, Spache published a revised version. We use this today. The revised version was created in 1978. This is what he had to say about this decision:

“If a readability formula is to continue to reflect accurate estimates of the difficulty of today’s books it, too, must change.” 

When is the Spache Readability Formula most useful?

The Spache Readability Formula is best used for children below the fourth grade. It is useful, for parents to know that reading books with the appropriate rating will be clear for their child. Spache is also invaluable for teachers.

If you’re reading for or writing to young children, Spache will quickly and accurately tell you if they're likely to understand.

Laura Kelly

Laura is a Marketing Executive at Readable. She loves coffee, literature, weightlifting and film photography.