Newsletter readability: the Flesch 60-70 sweet spot
TL;DR
Target Flesch reading-ease 60-70 (grade level 8-10) for general newsletters. B2B and technical can run 50-60 (grade 11-12). Anything below Flesch 50 loses casual readers. Three editing moves do most of the work: shorten sentences to 16-22 words, swap 3-syllable Latin words for 1-2 syllable Anglo equivalents, break paragraphs into 2-3 sentence chunks.
The most common readability mistake in newsletters is not writing too simply. It is writing too academically. The second most common is writing too short - sub-90-second emails read as unfinished and convert worse than 3-minute deep dives in almost every niche we have measured. The right target sits in a narrower band than the conventional advice ("write at a 6th-grade level!") suggests.
What Flesch reading-ease actually measures
Flesch reading-ease is a 0-100 number. Higher is easier. The score is calculated from two ratios: average sentence length (words per sentence) and average syllables per word. Both up means harder; both down means easier. A 100-word paragraph with 30-word sentences full of polysyllables scores around 35 (graduate-level reading). The same paragraph with 14-word sentences and shorter words scores around 65 (general adult reading).
The grade-level conversion - Flesch-Kincaid Grade Level - turns the score into a US grade equivalent. Grade 8-10 corresponds roughly to Flesch 60-70. Grade 11-12 corresponds to Flesch 50-60. Above grade 13 (Flesch under 50) the prose reads as effortful for most adult readers.
The niche-specific sweet spots
Different audiences tolerate different reading levels. Here are the median values we see across the corpus, refreshed quarterly:
B2B SaaS: 52 (grade 11.4) - technical readers, longer sentences, jargon tolerance.
Ecommerce: 71 (grade 7.8) - skim-readers, short bursts, direct CTAs.
Media / news: 62 (grade 9.6) - the AP-style sweet spot.
Creator / personal: 74 (grade 7.2) - conversational, second-person, sentence-fragment friendly.
Fintech: 48 (grade 12.6) - regulatory disclosures push it higher.
Developer / DevTools: 44 (grade 13.1) - code blocks and technical specificity dominate.
Notice the asymmetry. Ecommerce and creator newsletters live in the easy band; B2B SaaS, fintech, and dev are pulled toward technical reading levels by their content. The right target is not the global median - it is the niche median plus a small adjustment for your audience's specific composition.
The three editing moves that drop grade level fastest
1. Shorten sentences to 16-22 words
The single biggest lever. Average sentence length drives roughly half of the Flesch score. A draft averaging 28-word sentences scores 8-10 points lower than the same draft cut to 18-word sentences. The mechanical fix is to find every comma and ask whether it should be a period instead.
2. Swap Latin polysyllables for Anglo equivalents
"Utilise" becomes "use." "Demonstrate" becomes "show." "Leverage" becomes "use" (again). "Implement" becomes "ship" or "build." "Facilitate" becomes "help." Each swap drops syllable count, which drops the second half of the Flesch score. The prose gets sharper as a side effect.
3. Break paragraphs into 2-3 sentence chunks
Paragraph length does not directly affect Flesch but it dramatically affects perceived readability and scroll-through. A 6-sentence wall of text reads as effortful even if the sentences inside are short. Break it into two 3-sentence paragraphs and the same content reads 2x faster.
What about reading time?
Reading time is the other half of the readability story. Calculated at 240 words per minute (the standard screen-reading rate), it tells you how long the reader will spend on the email. The sweet spots:
- Under 90 seconds: reads as unfinished. Conversion lower than 2-minute equivalent.
- 2-4 minutes: the sweet spot for general-audience newsletters. Highest open-to-click ratio.
- 5-7 minutes: right for deep-dive editorial and Sunday long-reads.
- 10+ minutes: 60+ percent of readers drop off before the end. Split into a series.
Lexical diversity: the secret third metric
Flesch and grade level are the headline numbers. Lexical diversity is the quiet one that separates good prose from tired prose. It is the ratio of unique words to total words in the email body. Above 0.55 reads varied; below 0.40 reads repetitive.
The fix when diversity is low: identify the most overused tokens. The usual suspects are "just," "really," "very," "that," "thing," and "also." Each one can probably be deleted without changing meaning. Replace with stronger or simply absent words and the diversity number climbs along with the prose quality.
Score your draft live
The live newsletter counter gives you Flesch, grade level, reading time, and lexical diversity on every keystroke - no signup needed. The readability calculator covers the niche benchmarks and the methodology behind each metric.
Open the live counter →Frequently asked questions
What is a good Flesch score?
60-70 (grade 8-10) for general newsletters. 50-60 acceptable for B2B and technical. Below 50 loses casual readers.
How do I lower grade level?
Three moves: shorten sentences (16-22 words), swap polysyllables for short equivalents, break paragraphs into 2-3 sentence chunks.
Does shorter mean better?
No - under 90 seconds reads unfinished. 2-4 minutes general, 5-7 deep-dive, 10+ minutes loses 60% of readers.
What is lexical diversity?
Unique-word ratio. >0.55 varied, <0.40 repetitive. Cut overused tokens (just, really, very, that, thing).
Does Flesch work in non-English?
Flesch is English-tuned. Returns a number for any language but is flagged as English-calibrated.