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Sentence Length Average Calculator

Work out sentence length average instantly with clear inputs, formula shown and shareable results.

About Sentence Length Average Calculator

Average sentence length is the single strongest surface predictor of readability. Twelve hundred words in 62 sentences averages 19.4 words - moderate, with the longest sentence 2.5 times the average. Plain English guidance recommends 15-20 words on average, with deliberate variation rather than uniformity.

Formulas

Average sentence length

average = total words / total sentences

Variation

longest divided by average shows how uneven the rhythm is

Worked example

With the default values below, Sentence Length Average Calculator returns Average Sentence Length of 19.35. Change any input above and every figure here is recalculated in your browser.

Inputs used

Total wordsminimum 1
1,200
Total sentencesminimum 1
62
Longest sentenceminimum 1 words
48 words

Results

Average Sentence Length
19.35 words
Longest Sentence Relative To Average
2.48 x
Sentences Per Hundred Words
5.17
Assessment
Moderate - readable for most audiences

Step by step

  1. 1Values used
  2. 2Average sentence length
  3. 3Variation
  4. 4Average Sentence Length= 19.35 words
  5. 5Longest Sentence Relative To Average= 2.48 x
  6. 6Sentences Per Hundred Words= 5.17
  7. 7Assessment= Moderate - readable for most audiences

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Should every sentence be short?

No. Uniformly short sentences read as staccato. Vary length deliberately and keep the average moderate.

What about the longest sentence?

A ratio above about three times the average usually marks a sentence trying to do too much, and it is the first candidate for splitting.

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