Internal Storage size is less than

I have the Micromax Canvas A1 AQ4501 device. On various pages, as as this one, it's internal memory is listed as 4GB.

But, when I go to Settings -> Storage, under Internal Storage it says total space is 2.27 GB. The app Hardware Info also lists a similar amount: 2322 MB.

Where is the rest of my storage? :O

(Is it that the rest of the storage is taken up by OS etc, duh?)