Readability score checker

Paste English text to get its Flesch Reading Ease, Flesch-Kincaid grade, Gunning Fog, SMOG, Coleman-Liau and ARI scores, plus word, sentence and syllable counts, reading time and a list of long sentences. Free, no sign-up, and the same results are available as a JSON API.

Your text is sent to this site's API, scored in memory and discarded. It is never stored or logged (privacy).

Use the API

curl -s https://plaingrade-api.mike-tusa.workers.dev/v1/score \
  -H 'content-type: application/json' \
  -d '{"text":"The cat sat on the mat. It was happy.","lang":"en"}'

Get a free key (100 requests/day, commercial use OK): curl -s -X POST https://plaingrade-api.mike-tusa.workers.dev/v1/keys -H 'content-type: application/json' -d '{}'. Full reference: API docs.

{
  "mcpServers": {
    "plaingrade-api": {
      "type": "http",
      "url": "https://plaingrade-api.mike-tusa.workers.dev/mcp"
    }
  }
}

How the scores are computed

• Sentences: our own splitter. It knows common abbreviations (Mr., Dr., e.g., i.e., U.S., a.m., etc.), decimals (3.14), ellipses, quotes ("Why?" she asked), Wikipedia-style citations ([1]), URLs and e-mail addresses. Each list/bullet item, heading and blank-line-separated paragraph is its own sentence; a single line break inside a paragraph is treated as a space.
• Words: runs of letters/digits, keeping apostrophes, hyphens and inner dots (don't, well-known, 3.14 and U.S. are one word each). A URL or e-mail address is one word of one syllable. Citation markers like [1] and bullet markers are not words.
• Syllables: the syllable library, per word part (well-known = well + known); a number counts as one syllable. Syllable counts come from a spelling-based heuristic, not a pronunciation dictionary. They are right for about 95% of common English words, so scores can differ by a few points from other tools (e.g. textstat, Hemingway) that count syllables differently.
• Letters (Coleman-Liau, ARI): letters and digits inside words.
• Complex words (Gunning Fog): 3+ syllables, excluding proper nouns (capitalised, not first in the sentence), hyphenated words, and words that reach 3 syllables only through -es, -ed or -ing. Polysyllables (SMOG): every word with 3+ syllables.
• Flesch Reading Ease = 206.835 − 1.015 × (words/sentences) − 84.6 × (syllables/words). Flesch-Kincaid grade = 0.39 × (words/sentences) + 11.8 × (syllables/words) − 15.59. Gunning Fog = 0.4 × (words/sentences + 100 × complex/words). SMOG = 1.043 × √(polysyllables × 30/sentences) + 3.1291. Coleman-Liau = 0.0588 × L − 0.296 × S − 15.8 (L = letters per 100 words, S = sentences per 100 words). ARI = 4.71 × (letters/words) + 0.5 × (words/sentences) − 21.43. Consensus grade = the mean of the five grade-level scores.
• Scores are not clamped: Flesch Reading Ease can go below 0 or above 100, and grades can be negative for very simple text. Reading time assumes 238 words/minute; speaking time 150 words/minute.
• English only. Scores are unstable under ~100 words, and SMOG was designed for 30+ sentences; the response flags both in notes.

Pricing

Paid tiers are not available yet.

Questions or abuse reports: digitalpromohub.support@gmail.com.