A sentence counter is a free online tool that counts the sentences in your text and reports the average words per sentence. It also highlights your longest sentence, helping writers, students and editors keep their writing clear and readable.
Longest sentence
What is a good average sentence length?
Short answer: Aim for 15 to 20 words per sentence for general writing like blog posts and emails. Academic and technical writing can run 20 to 25 words, while marketing copy and fiction often stay under 15. If your average climbs past 25 words, your readers are working too hard. Paste your text into the sentence counter to check.
Average alone is not enough: variety matters. A string of identical-length sentences feels robotic. Mix short punchy sentences with longer flowing ones, and use the longest-sentence readout to find run-ons that should be split in two.
How does the sentence counter work?
Short answer: The counter splits your text on full stops, question marks and exclamation marks, then counts each resulting chunk that contains at least one letter or number. The average words per sentence is the total word count divided by the sentence count. The longest sentence is measured by word count and shown in full.
Abbreviations like 'Mr.' or 'e.g.' can occasionally split a sentence early, so treat the count as a strong guide rather than a legal ruling. For normal prose the results are accurate, and everything is computed instantly in your browser.
Why count sentences instead of words?
Short answer: Word counts tell you about length; sentence counts tell you about readability. Two 500-word articles can feel completely different if one averages 12 words per sentence and the other averages 30. Editors and teachers use sentence length as a quick proxy for clarity, and SEO guides often recommend shorter sentences for web content.
Pair this tool with the word counter: use words for hitting length targets and sentences for keeping the writing digestible. Together they give you a fast readability check on any draft.
Frequently asked questions
Is this sentence counter free?
Yes, free and unlimited with no account. Count sentences in as many documents as you like.
How does it detect sentences?
It splits text on periods, question marks and exclamation marks, then ignores fragments without letters or numbers. Abbreviations can occasionally cause an extra split.
What is a good average sentence length?
15 to 20 words suits most writing. Over 25 on average suggests your text may feel heavy and hard to follow.
Does it work with other languages?
It works with any text that ends sentences with . ? or !, which covers most European languages. Languages with different sentence-ending punctuation may not split correctly.
Is my text stored anywhere?
No. Everything runs in your browser, so your writing stays private on your device.