The Flesch formulas have scored readability since the 1940s: average sentence length plus syllables per word, out comes a 0–100 ease score and a school grade level. The formulas are public — what varies between tools is everything around them.
Our readability calculator does the surrounding parts right:
- A band, not just a number — 65.8 means little on its own; “65.8 — Standard” tells you where you sit, from Very easy (90+) down to Very difficult (below 30).
- Grade level alongside — Flesch-Kincaid, computed from the same counts, plus the raw words, sentences, and syllables so you can see what’s driving the score.
- Honesty about syllables — no software counts English syllables perfectly. We use a documented vowel-group heuristic and say plainly that scores may differ a few points from other checkers.
- Private by design — drafts are often unpublished, so the analysis runs entirely in your browser and never touches the URL.
Edit, re-paste, watch the direction of the score — that loop is the whole game.
Content team wiki? The calculator is embeddable with one iframe.