What the five scores measure
Flesch Reading Ease estimates ease from words per sentence and syllables per word. Flesch–Kincaid Grade expresses those factors as a US grade estimate. Gunning Fog adds the share of complex words; this implementation heuristically excludes capitalized names and some suffixes.
SMOG estimates grade from polysyllabic words and is intended for 30-sentence samples. ARI uses characters per word and words per sentence. These are screening signals, not assessments of voice, meaning or story quality.
Worked revision: keep the meaning, reduce the load
Before: ‘Despite the apparent absence of personnel within the station, Mara proceeded to investigate the illuminated ticket office, where she discovered an object she believed had been permanently lost.’
After: ‘The station looked empty. A light burned in the ticket office. Mara went closer. On the counter lay the watch she thought she had lost.’
The revision separates observation from discovery and replaces vague phrases with concrete action. It also changes the rhythm: a slow, formal narrator might prefer parts of the first version. Read both aloud before deciding.
A score is a starting point, not a writing rule
If a passage feels hard to follow, check whether the reader knows who is acting, where they are and what changed. Then look at sentence length and unnecessary abstraction. A clear long sentence can work better than several choppy ones.
For a fuller review, combine the numbers with reader feedback. Metaphor, suspense, cultural knowledge and intentional ambiguity are outside these formulas.