Substack Readability Checker
Paste your content to get a standard Flesch Reading Ease score, grade level, and the specific long sentences dragging it down. Free, no signup, nothing leaves your browser.
Nothing you type here is sent anywhere - this runs entirely in your browser.
Paste content above (or try the example) to see your readability score.
About the Flesch Reading Ease formula
Flesch Reading Ease is a decades-old, widely used readability formula based on two measurable inputs: average sentence length and average syllables per word. It produces a score from 0 (very hard to read) to 100 (very easy), and a related Flesch-Kincaid Grade Level estimates the U.S. school grade a reader would need to follow the text easily.
Syllable counting here uses a standard approximation algorithm, not a dictionary lookup, so treat the exact score as a close estimate rather than an exact measurement. The real value is in the specific long sentences it flags - those are concrete, fixable issues regardless of the precise numeric score.
Questions
What is the Flesch Reading Ease score?
A standard readability formula from 0 (very hard to read) to 100 (very easy), calculated from average sentence length and average syllables per word - widely used across writing and editing tools.
How accurate is the syllable counting?
It uses a standard approximation algorithm rather than a dictionary lookup, so it's very close but not perfectly exact for every word. Treat the score as a close estimate, not a precise measurement.
What's a good Flesch Reading Ease score for a newsletter?
Scores of 60-80 (Standard to Fairly Easy, roughly 7th-9th grade level) are a reasonable target for general newsletter writing - conversational without being simplistic.
How is this different from the Post Analyzer?
This tool uses the formal Flesch Reading Ease formula (sentence length + syllable count). The Post Analyzer scores 8 broader structural categories like hook, CTA, and scannability using simpler word-count heuristics.