Definitions for each of the readability tests used
| Name of test | Scoring basis | Description of test | Formula |
| Flesch-Kincaid Reading Grade Level | Grade level | Developed by the Navy to assess readability of technical documents. Suitable for assessment of a vast range of documents, often used in education. It generates a score determining the equivalent level of US level education needed to understand the piece of text | (11.8 × ASW) + (0.39 × ASL) −15.59 |
| Flesch-Kincaid Reading Ease | Index score | Index score ranging from 0 to 100, with higher scores denoting easier readability. Score over 65 is deemed to be an acceptable readability level which is accessible to most people. | (206.835 − (84.6 × ASW) − (1.015 × ASL) |
| ARI | Grade level | Designed to gauge the understandability of a text. Unlike other indices, relies on characters per word instead of syllables. | 4.71 (characters/words)+0.5 (ASL) – 21.43 |
| Gunning Fog | Grade level | This index estimates the years of formal education required to understand a text on first reading. Developed to assist American businesses improve the readability of their writing. Applicable to numerous disciplines. | 0.4 × (ASL+((C**/W) × 100)) |
| Simple Measure Of Gobbledygook | Grade level | Tests for 100% comprehension of a document on first reading, whereas most formulas test for around 50%–75% comprehension. Most accurate when applied to documents ≥30 sentences in length. This test is widely used in checking health messages | 1.0430 × √C+3.1291 |
| Coleman-Liau | Grade level | Designed for secondary age (fourth grade to college level) readers. Approximates the level of reading required to comprehend a text. Applicable to numerous sectors. Relies on characters instead of symbols per word | 0.0588L-0.296S-15.8 |
.ASL, number words/number sentences; ASW, number syllables divided by number of words; C**, complex words with exceptions including, proper nouns, words made 3 syllables by addition of "ed" or "es", compound words made of simpler words; C, complex words (≥3 syllables); L, average number of letters per 100 words; N, number of syllables; RGL, reading grade level; S, average number of sentences per 100 words; W, number of words.