This tutorial will show you how to get the number of page in a pdf file using C#.NET

We will use itextsharp to read a pdf file, itextsharp is an open source library that helps you create a pdf or manipulate data with pdf files

If you haven't got itextsharp in your project, you can download and install it from manage nuget packages

string path = "C://sample.pdf";
PdfReader pdfReader = new PdfReader(path);
int numberOfPages = pdfReader.NumberOfPages;

You can use NumberOfPages to get how many number of pages in a pdf file