The Power-Sumner-Kearl Readability Formula

Step 1: Select a sample passage of around 100 words.

Step 2: Calculate the exact number of words and sentences in the sample passage.

Step 3: Divide the number of words with the number of sentences to arrive at Average Sentence Length (ASL)

Step 4: Apply the formula:

GL = 0.0778(ASL) + 0.0455(NS) – 2.2029

TO GET THE (NS) VALUE: Divide total number of syllables in the passage into the total number of words. This will give you the average syllable length. Multiply the average syllable length with 0.0455. Then multiply this number with 100. The final number is the number of syllables (NS). (Note: do not multiple this number with .0455 again).

GL = US Grade Level

ASL = Average Sentence Length

NS = Number of Syllables

Step 6: The Reading Age is determined by applying the following formula:

RA = 0.0778(ASL) + 0.0455(NS) + 2.7971

Where,

RA = Reading Age

ASL = Average Sentence Length

NS = Number of Syllables