Size of a library and the executable

Question

I have a static library *.lib created using MSVC on windows. The size of library is say 70KB. Then I have an application which links this library. But now the size of the final

Answer 1

There is additional bookkeeping information in the .lib file that is not needed for the final executable. This information helps the linker find the code to actually link. Also, debug information may be stored in the .lib file but not in the .exe file (I don't recall where debug info is stored for objs in a lib file, it might be somewhere else).