ThinkForU PDF Sentence Counter
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Reading PDF…0%
0
Total Sentences
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0
Words
0
Characters
0
Chars (no spaces)
0
Paragraphs
0
Pages
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Unique Words
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Reading Time
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Speaking Time
Avg. Sentence Length
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Avg. Word Length
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Sentences per Paragraph
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Readability Est.
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Longest Sentence
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What This Tool Counts
- Sentences — ending with . ! ? or similar punctuation
- Words — total word count across all pages
- Characters — with and without spaces
- Paragraphs — text blocks separated by blank lines
- Unique words — distinct vocabulary count
- Reading time — at 238 words per minute (avg. adult)
- Speaking time — at 130 words per minute (avg. speaker)
- Avg. sentence length — words per sentence
- Longest sentence — full text of the longest sentence found
- Readability — estimated grade level (Flesch-Kincaid)
How It Works
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1
Upload your PDF — drag, drop or click to select. Works on all modern browsers.
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2
Click Analyse PDF — PDF.js extracts all text from every page locally.
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See full statistics — sentences, words, characters, reading time, and more instantly.
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- PDF never uploaded to any server
- All analysis runs in your browser using PDF.js
- Safe for confidential documents
- No signup · No limits · 100% free
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Free PDF Sentence Counter — Count Sentences, Words & More in Any PDF
The only dedicated PDF sentence counter online. Most word counters ignore sentences — this tool makes sentences the primary metric while giving you a complete text analysis: words, characters, paragraphs, reading time, average sentence length, longest sentence, and a readability estimate. All processed 100% in your browser using Mozilla PDF.js — your file never leaves your device.
Who Uses a PDF Sentence Counter?
Students & Academics
Check essay sentence counts before submission. Journals often require maximum sentence complexity for readability standards.
Writers & Editors
Analyse average sentence length to improve readability. Long average sentences (over 25 words) reduce comprehension.
Content Marketers
Verify PDF reports and whitepapers meet readability targets before publishing or sending to clients.
Translators
Count sentences in source PDFs to estimate translation scope, pricing, and turnaround time accurately.
Speakers & Presenters
Use speaking time estimates to check if a speech or presentation PDF fits within your allocated time slot.
Legal Professionals
Count sentences in contracts, briefs, and legal documents to measure complexity and review scope.
Frequently Asked Questions
How does this tool count sentences in a PDF?
PDF.js extracts all text from every page of your PDF. The extracted text is then split into sentences using a sentence boundary detection algorithm that recognises full stops, exclamation marks, question marks, and common abbreviations (e.g. "Dr.", "Mr.", "etc."). Abbreviations and decimal numbers are specifically excluded from being counted as sentence endings to improve accuracy.
Is my PDF uploaded to a server?
Never. This tool uses Mozilla PDF.js — an open-source JavaScript library that processes PDFs entirely in your browser. Your PDF is read into browser memory and analysed locally. No data is ever sent to any server. Safe for confidential documents including legal contracts, medical records, and research papers. See our Zero Data Storage Policy.
Why does it show 0 sentences for my PDF?
This happens when your PDF is a scanned document — the pages are images of text, not actual text characters. Scanned PDFs contain no readable text for the browser to extract. To count sentences in a scanned PDF, you would first need to run OCR (Optical Character Recognition) software to convert the images to text, then use this tool on the resulting text-based PDF.
What is a good average sentence length?
For most writing, an average of 15–20 words per sentence is considered ideal. Sentences under 10 words feel abrupt and choppy. Sentences over 25 words become harder to follow and reduce readability scores. Academic writing tends toward 20–30 words per sentence. Marketing and web content typically aims for 12–18 words per sentence for maximum clarity.
How is reading time calculated?
Reading time is calculated at 238 words per minute — the average silent reading speed for an adult, based on research published in the journal Reading Research Quarterly. Speaking time is calculated at 130 words per minute — the average speaking rate for a clear, measured presentation. Both figures are estimates; actual time varies by individual and content complexity.
What is the readability estimate based on?
The readability score uses an approximation of the Flesch-Kincaid Grade Level formula, which considers average sentence length and average word length. The result is an estimated US school grade level. Grade 8 means the text is readable by an average 8th grader. Most web content targets Grade 8–10. Academic papers typically score Grade 14–16. Note: this is an approximation since syllable counting is estimated from word length.