Headline analyzer
What is Flesch-Kincaid reading grade?
Flesch-Kincaid grade is a readability formula that estimates the US school grade level needed to understand a piece of text: FK grade = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59. Seeklyn scores headlines at FK grade 6–9 as ideal for a broad internet audience, awarding 100 points in that band and deducting 10 per grade outside it.
Reading Grade Level appears in the Readability sub-score panel of every headline analysis at /dashboard/headline.
What is Flesch-Kincaid reading grade?
Flesch-Kincaid grade is a readability formula published by Rudolf Flesch and J. Peter Kincaid, originally developed for US Navy training materials in the 1970s. The formula is: FK grade = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ word) − 15.59. A score of 8.0 means 8th-grade reading level; 12.0 means high-school senior level.
The formula has 2 variables: sentence length (words per sentence) and word complexity (syllables per word). Long sentences raise the score; polysyllabic words raise it further. For a headline — always 1 sentence — only the syllable-per-word variable drives complexity. Cutting either variable lowers the score and broadens the readable audience.
What is the Flesch-Kincaid formula?
The Flesch-Kincaid grade formula in full is:
FK grade = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59
Seeklyn implements this formula in `readabilityMetrics` in the headline package, counting syllables with a vowel-group heuristic that is approximately 95–98% accurate for English. For a headline specifically, sentences is always 1, so the formula reduces to: FK grade = 0.39 × words + 11.8 × (syllables ÷ words) − 15.59. The result is rounded to 1 decimal place.
What FK grade does Seeklyn consider ideal?
FK grades 6–9 are Seeklyn's ideal band for headlines targeting a broad internet audience. Grade 6 corresponds to a US 6th-grader (age 11–12); grade 9 to a 9th-grader (age 14–15). Most mainstream web readers are comfortable up to grade 8–9; USA Today targets grade 7–8.
Seeklyn's readability sub-score awards 100 points for a grade in the 6–9 band, then deducts 10 points per grade outside the band, with a floor of 40 for grades below 6 and a floor of 0 for very high grades. An FK grade 11 headline — 2 grades above the ideal upper bound — loses 20 readability points and scores 80. FK grade 13 scores 60; grade 15 hits the floor at 0.
| FK Grade | Approximate level | Readability sub-score |
|---|---|---|
| Below 6 | Simpler than 6th grade | 40 (floored, -10/grade below 6) |
| 6–9 | Ideal band (6th–9th grade) | 100 |
| 10 | 10th grade | 90 |
| 11 | 11th grade | 80 |
| 12 | 12th grade / high school | 70 |
| 13 | College freshman | 60 |
| 14+ | College and above | 50 or lower, floor 0 |
How does Seeklyn count syllables?
Seeklyn counts syllables using a vowel-group heuristic: it counts runs of contiguous vowels (including y) in the lowercase word, then subtracts 1 for a trailing silent "e" (e.g. "cake" → 1 syllable, not 2), and guarantees a floor of 1. This approach is approximately 95–98% accurate for English and requires no dictionary lookup. Irregular words like "hour" or "beautiful" may be off by 1 syllable, which causes a fractional FK grade rounding error — inconsequential for the 0–100 sub-score.
Frequently asked questions
Is a lower or higher FK grade better for headlines?
Lower is generally better for broad audiences, but not too low. Seeklyn's ideal band is grade 6–9. Below 6, the headline may read as oversimplified or vague; above 9, it starts to lose casual readers. The goal is accessible without being shallow.
Why does Seeklyn use grade 6–9 as the ideal band?
Grade 6–9 matches the reading comfort zone for most adult internet users and aligns with mainstream publisher guidelines (e.g. USA Today targets grade 7–8). It is also the band where headlines tend to balance concrete specificity with skimmability — high enough to carry meaningful words, low enough to scan in under 3 seconds.
Does FK grade apply to body content too?
Yes, though Seeklyn's ideal band for longer content is similar: the passage-citability rubric also favors clear, concrete sentences readable at roughly grade 6–10. FK grade is most actionable for headlines because a single word swap can shift the grade noticeably. For body content, sentence length is the stronger lever.