*Only the most important ones are listed.
246 TMS Entertainment
184 Production IG
159 Kyoto Animation
150 Studio Pierrot
150 Studio Deen
140 Studio Ghibli
130 Mad House
70 Bee Train
70 Synergy SP
38 A-1 Pictures
20 Brain's Base
*Gainax and Sunrise is known for their efficiency. They tend to minimize budget taken from animation as much as possible; most of Sunrise animations are actually animated by other small subcontracted studios from Japan/Korea/Taiwan. Kyoto Animation is quite opposite; they uses their in-house staffs on almost everything.
*PA works have their own team of staffs who are specialised for 'animation' part. That's why their animation always have high-quality movement and drawings.
*Number of staffs in 'Shaft' is in mystery, but it is known for being very small. They needed a lot of other animating studios in subcontract recently; in case of 'Dance in the Vampire Bund', every thing was almost entirely drawn, edited by A.C.G.T.
* All these are from the latest database available.
Source: From my personal data basis collected from 2ch
Article posted by sirn
Updates: P.A. Works staff info changed