Sentence counter that names the long ones

No — the period after Dr. is recognised as part of the abbreviation and passed over. Forty-seven abbreviations are treated this way, including Mr, Mrs, Prof, St, vs, etc, Inc, Ltd, the months and the days of the week, and any single letter followed by a period is read as an initial, which is what keeps U.S., e.g., i.e. and J. R. R. Tolkien in one piece. The panel at the foot of the tool names every period it passed over, so you can check the decision rather than trust it.

Yes, one per line, even when there is no full stop at the end. A line break is treated as the end of a sentence in its own right, because a heading, a list item or a table row is a complete unit that should not be glued onto the paragraph beneath it. Those lines are marked “no full stop” in the list, so a document that suddenly reports far more sentences than you expected can be traced to its headings and bullets in a moment.

None of them ends a sentence: a period only counts when a space or the end of the line follows it. That leaves 3.14, $18.50 and version 2.1 intact, because the character after the period is a digit. A run of marks is treated as one ending, so “Really?!” and a trailing ellipsis each close a single sentence rather than two or three, and a closing quote or bracket after the mark is kept with the sentence it belongs to.

Almost always because of the parts of a document that are not prose. Word only shows a sentence count inside its Readability Statistics box, which appears at the end of a spelling and grammar check, and it counts whatever is in the document — headings, captions, table cells, footnotes — using its own grammar engine. This page counts what you pasted, splits at every hard line break, and applies a published list of 47 abbreviations. Paste only the body text and the two totals normally land within a per cent of each other; paste a document full of headings and they will not.

That is the flag for a break that was probably wrong, and it is worth looking at. A sentence beginning in lower case usually means a period was read as a full stop when it was really part of something else: an abbreviation outside the list of 47 (approx., cf., no., ibid.), an initialism written with spaces, or a decimal typed as “1. 5”. The count is not silently corrected, because guessing would be worse than reporting; the flag tells you where to look and you can rewrite the line if it matters.

Your text still has the hard line breaks the PDF put in, and each of them ends a sentence here. Copying out of a PDF, an email client or a plain-text file gives you lines of about seventy characters with a real line break at the end of each, so a forty-word sentence arrives as four lines and is counted as four sentences. Rejoin the paragraphs with the remove line breaks tool first and then count — the total drops sharply and lands where it should.

Aim for an average of 15 to 20 words and treat anything past 30 as a candidate for surgery. A much-quoted newspaper readability study found that readers grasped almost everything in an 8-word sentence, around 90 per cent at 14 words, and under 10 per cent once a sentence passed 43. Averages matter less than variety, though: a page of uniform 18-word sentences is exhausting in a different way, so the bands above are there to show you a mixture rather than a target.