Readability Checker
Paste an email. See its Flesch reading ease, grade level, and sentence-length distribution. No AI, just math.
How this works
People read marketing email at roughly 250 words a minute, in a skim pattern that resembles an F-shape: first line, opening of each paragraph, last line, CTA. Anything that slows the skim hurts conversion.
We compute two standard readability metrics. Flesch Reading Ease is a 0–100 score where higher is easier (aim for 60+ for general audiences). Flesch-Kincaid Grade Level tells you the US school grade required to parse the text — most great emails hit between grade 5 and 8.
We also chart sentence-length distribution. The pattern that correlates with high engagement is bursty: short sentences (under 8 words) interleaved with the occasional longer one. If your histogram is dominated by 16-25 word sentences, you're putting the reader through cognitive load they didn't sign up for.
This tool runs entirely server-side with no AI — math you can trust, in milliseconds. Free as long as you want to use it.
Want this on every email you send?
Sign up free and get unlimited runs of every tool, plus a one-screen editor that rewrites, scores, and generates subject lines, preheaders, and CTAs in seconds.