It will depend on the card. When you change to shoot raw, the camera should tell you how many images you have on that card. Record how many it says in jpeg and then change it and see how many it says with RAW.
1) Photos in JPEG or RAW or any format are not of a fixed size and more complex scenes will generally result in bigger file sizes.
2) The back of hte camera/viewfinder normally shows the estimated number of remaining shots possible with the card currently installed in the camera
3) RAW photos will be bigger than JPEG; they also take longer to write to a card so you will see the total number of shots and the number of shots you can get in a burst go down. However most photographers consider the editing and quality potential gains of RAW worth that sacrifice
With the camera set to it's highest quality setting the ratio is about 1:4.
You would be able to record about 4x more JPEG files than Raw files. Tutorials – The RAW File Format
Image file size varies with image content.
A photo of a blank wall will be a smaller image file than a photo of the same wall with art work hanging on the wall and some furniture in the shot.
The number of images (JPEG or Raw) your memory card has room left for that is displayed on your camera is an approximation.
FWIW -JPEG is an acronym for an image file format developed by the Joint Photographic Experts Group. So the whole thing gets capitalized - JPEG
Raw is not an acronym, so it's Raw, not RAW.
There are over 100 Raw image file types - CR2, 3FR, ARI, PEF, CRW, PTX, MEF, DNG, X3F, yada, yada, yada.
Nikon's Raw image file type is NEF - Nikon Electronic File.
In fact, each new digital camera Nikon releases has it's own unique NEF file type, which is why it takes Adobe some weeks to reverse-engineer each new file type for Adobe Camera Raw.
The question should be, what is the cost of NOT shooting in raw? Having the camera produce JPG images locks so many things away from you.
Memory consumption is the LAST thing I worry about when shooting. Not since my first Sony compact point-and-shoot that came with a 64 megabyte card have I worried about having enough space in the camera to shoot with.