Identify your iPad by referring to the model number printed on the back of your device

IPAD MODEL NUMBERS:

1st Generation: Model A1337 or A1219 (no camera). 
2nd generation: Model A1396, A1397, or A1395 (camera and 30-pin connector)
3rd generation: Model A1430, A1403 or A1416 (Siri, HD camera, 30-pin connector). 
4th generation: Model A1460, A1459, or A1458 (retina display and lighting connector)
iPad Mini: Model A1455, A1454 or A1432 (7.9" screen)
iPad Air: Model A1474 or A1475 (lightning cable)

How Do I Tell My iPad's Capacity?

1. Simply navigate to Settings > General > About.
2. Scroll down to the Capacity section.
Here you will see the gigabytes (GB) of your iPad.

NOTE The total capacity might not be reflected correctly if you have used part of your GB capacity for files or apps already.
The most accurate way to see the capacity is after wiping your iPad. If you have a 16GB iPad for example you might see 15.5 GB.