How the average is calculated
Average sentence length is the total word count divided by the sentence count. Sentences are split the same way the sentence counter splits them: a run of text followed by one or more of ., !, or ?. Each sentence is then trimmed of surrounding whitespace before it is measured, so leading spaces and line breaks never inflate a count.
Words inside each sentence are matched with the same pattern the word counter uses by default, so a contraction like don't and a hyphenated compound like well-known each count as one word. That means the Words figure on this page and the total on the word counter agree for the same input, and the average is not skewed by a different tokenizer.
One split rule differs from the sentence counter, and it is deliberate. Text that ends without ., !, or ? leaves a trailing fragment, and a headline or a single unpunctuated line is entirely fragment. Count Fragment is on by default so that text still measures instead of returning zero. Turn it off to count punctuation-terminated sentences only, which reproduces the sentence counter's number exactly.
Two optional readouts add detail without changing the average. Long / Short appends the longest and shortest sentence with its position, which is where an outlier usually hides. Per Sentence lists every sentence length in order, so you can scan a whole draft for the run-on.
How to use average sentence length
- 1Paste or type the text you want to measure into the input panel.
- 2Read the average, the sentence count, and the word total in the output panel.
- 3Switch Unit to Characters to measure sentence length in characters instead of words.
- 4Turn on Long / Short to see which sentence is the longest and which is the shortest.
- 5Turn on Per Sentence to list the length of every sentence in order.
Keyboard shortcuts
Drive TextResult without touching the mouse.
| Shortcut | Action |
|---|---|
| Ctrl F | Open the find & replace panel inside the input Plus |
| Ctrl Z | Undo the last input change |
| Ctrl Shift Z | Redo |
| Ctrl Shift Enter | Toggle fullscreen focus on the editor Plus |
| Esc | Close find & replace, or exit fullscreen |
| Ctrl K | Open the command palette to jump to any tool Plus |
| Ctrl S | Save current workflow draft Plus |
| Ctrl P | Run a saved workflow Plus |
What this tool actually does
Terminator-based sentence split
A sentence is a run of text closed by one or more of ., !, or ?. Repeated terminators close a single sentence, so Wait!!! counts once. Abbreviations such as Dr. or e.g. do close a sentence under this rule, which nudges the average down on text that is heavy with them.
Trailing fragment counts by default
Count Fragment is on, so text after the last terminator counts as one more sentence when it contains at least one word character. Turn it off and only punctuation-terminated sentences are measured, which matches the sentence counter exactly.
Word matching shared with the word counter
Words are matched as [\w']+(?:-[\w']+)*, the word counter's default pattern. don't is one word, well-known is one word, and a bare - or & is none. The reported Words total therefore matches word counter output for the same text.
Character mode measures trimmed sentences
With Unit set to Characters, each sentence is measured after trimming, and the count includes internal spaces and the closing punctuation. The footer line switches from Words to Characters so the division stays checkable.
Decimals are clamped, never thrown
Decimals sets how many places the average shows, from 0 to 6 in the control. A value typed outside that range is clamped rather than erroring, and a non-numeric entry falls back to 0 places.
Worked example
The second sentence has no closing punctuation, so it only counts because Count Fragment is on. Turn that toggle off and the same input reports 3.00 words across 1 sentence.
Keep it short. This second sentence is a good deal longer than the first
Average sentence length: 7.00 words Sentences: 2 Words: 14
Settings reference
| Setting or behaviour | Effect on output |
|---|---|
| Sentence split | A run of text closed by one or more of ., !, or ?. Each sentence is trimmed before measuring. |
| Unit (default Words) | Words measures each sentence with the word counter's pattern; Characters measures the trimmed sentence length. |
| Decimals (default 2) | Decimal places on the average. Out-of-range values are clamped, non-numeric falls back to 0. |
| Count Fragment (default on) | Counts a final run of text with no closing punctuation as one sentence. Off matches the sentence counter. |
| Long / Short (default off) | Appends the longest and shortest sentence length with its position in the text. |
| Per Sentence (default off) | Appends one line per sentence with its measured length, in reading order. |
| Empty input | Reports an average of 0 and a sentence count of 0 rather than erroring. |
FAQ
What is a good average sentence length?
Why does my sentence count differ from the sentence counter?
., !, or ? counts as a sentence so unpunctuated lines still measure. Turn the toggle off and the two pages report the same number.Are abbreviations treated as sentence endings?
Dr., e.g., and U.S. each close a sentence. On text dense with abbreviations the sentence count runs high and the average runs low. There is no abbreviation dictionary.Does it count hyphenated words and contractions as one word?
well-known is one word and don't is one word, matching the word counter defaults so the two totals agree for the same input.