Size of a package: "Installed-Size" vs "Size"

I am trying to find out a package size. I tried the following command:

$ apt-cache show mlocate | grep Size
Installed-Size: 252
Size: 50136

Does "Installed-Size" mean size after unpacking the package? while "Size" means the size in RAM?

Solution 1:

Installed-Size is the space the installed package will probably occupy on your disk. According to the Debian docs, it's technically "the integer value of the estimated installed size in bytes, divided by 1024 and rounded up." The actual outcome might vary, depending for example on properties of your file system (like the block size) or whatever any maintainer scripts in the package may be doing (for example, setting up config files).

Size is just the size of the deb package file.