Flesch-Kincaid Readability Calculator

Flesch-Kincaid Readability is evaluated from Total Words in Text, Total Sentences and Total Syllables. The calculation reports Flesch Reading Ease Score, Reading Ease Level and Flesch-Kincaid Grade Level.

Results

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About the Flesch-Kincaid Readability Calculator

Flesch-Kincaid Readability is treated here as a quantitative relation between Total Words in Text, Total Sentences and Total Syllables and Flesch Reading Ease Score, Reading Ease Level, Flesch-Kincaid Grade Level and Approximate Grade Equivalent.

The calculator uses a multi formula configuration. Each reported value is read as a direct evaluation of the stored rules with the declared field formats and units.

Formula basis:
FRE = 206.835 - (1.015 x avg sentence length) - (84.6 x avg syllables per word)
FKGL = (0.39 x avg sentence length) + (11.8 x avg syllables per word) - 15.59
Higher FRE score = easier to read. Lower FKGL = lower grade level required.

Interpret the outputs in the order shown by the result fields. Optional inputs affect only the outputs that depend on those variables.

Formula & How It Works

The calculation applies the following relations exactly as recorded in the metadata:

FRE = 206.835 - (1.015 x avg sentence length) - (84.6 x avg syllables per word)
FKGL = (0.39 x avg sentence length) + (11.8 x avg syllables per word) - 15.59
Higher FRE score = easier to read. Lower FKGL = lower grade level required.

Each output field is produced by substituting the supplied inputs into the relevant relation and then applying the declared rounding or text format.

Worked Examples

Example 1: Plain English text: 200 words, 10 sentences, 230 syllables

Inputs

total_words: 200 total_sentences: 10 total_syllables: 230
Flesch Reading Ease Score: 89.2. Reading Ease Level: Easy (6th grade - plain English). Flesch-Kincaid Grade Level: 5.8. Approximate Grade Equivalent: Middle school (Grades 6-8)

With Total Words in Text = 200, Total Sentences = 10 and Total Syllables = 230 as the stated inputs, the result is Flesch Reading Ease Score = 89.2, Reading Ease Level = Easy (6th grade - plain English) and Flesch-Kincaid Grade Level = 5.8. Each value corresponds to the declared output fields.

Example 2: Legal / academic text: 150 words, 5 sentences, 300 syllables

Inputs

total_words: 150 total_sentences: 5 total_syllables: 300
Flesch Reading Ease Score: 7.2. Reading Ease Level: Very Difficult (professional / academic / legal). Flesch-Kincaid Grade Level: 19.7. Approximate Grade Equivalent: Post-graduate / professional

With Total Words in Text = 150, Total Sentences = 5 and Total Syllables = 300 as the stated inputs, the result is Flesch Reading Ease Score = 7.2, Reading Ease Level = Very Difficult (professional / academic / legal) and Flesch-Kincaid Grade Level = 19.7. Each value corresponds to the declared output fields.

Example 3: Blog post: 400 words, 25 sentences, 480 syllables

Inputs

total_words: 400 total_sentences: 25 total_syllables: 480
Flesch Reading Ease Score: 89.1. Reading Ease Level: Easy (6th grade - plain English). Flesch-Kincaid Grade Level: 4.8. Approximate Grade Equivalent: Elementary school (Grade 5 or below)

With Total Words in Text = 400, Total Sentences = 25 and Total Syllables = 480 as the stated inputs, the result is Flesch Reading Ease Score = 89.1, Reading Ease Level = Easy (6th grade - plain English) and Flesch-Kincaid Grade Level = 4.8. Each value corresponds to the declared output fields.

Example 4: Children's content: 100 words, 10 sentences, 110 syllables

Inputs

total_words: 100 total_sentences: 10 total_syllables: 110
Flesch Reading Ease Score: 103.6. Reading Ease Level: Very Easy (5th grade, easy to read). Flesch-Kincaid Grade Level: 1.3. Approximate Grade Equivalent: Elementary school (Grade 5 or below)

With Total Words in Text = 100, Total Sentences = 10 and Total Syllables = 110 as the stated inputs, the result is Flesch Reading Ease Score = 103.6, Reading Ease Level = Very Easy (5th grade, easy to read) and Flesch-Kincaid Grade Level = 1.3. Each value corresponds to the declared output fields.

Common Use Cases

  • Calculate reading ease score for text
  • Determine grade level of writing
  • Check if writing is appropriate for target audience