Depends on how you are storing the images. If you are storing RAW files, then it's probably 6-8MB per picture. Jpeg file size depends on the quality of the JPEG you select. It could be up to 4-5MB for the highest quality JPEGs, and just a couple of hundred KB for the lowest quality image.
See the Question: How many pictures on 4GB memory card in 10.2 mega pixel digital camera?(How_many_pictures_on_4GB_memory_card_in_10.2_mega_pixel_digital_camera)
200
1GB MEMORY CARD CAN HOLD 150 TO 200 SNAP IN A 13.6 MEGA PIXEL CAMERA.
417
Roughly 200.
256
60000
Over 3000.
About 6-8 photos.
A camera with this pixel setting will have more room, but the images may not be as crisp as ones with a bigger pixel count. You can fit approximately 200 pictures of this kind on a 2 GB memory card.
It depends on the format. In JPEG, it's around 18.
How many pictures can a 4.0GB memory stick hold on a 12.0 mega pixel digital camera?