When doing replacement or upgrading on 1998 – 2011 BMW 323is 323Ci 323i capsule halogen headlamps HID with, the bulb size guide is necessary for you to take the reference.
Jump to corresponding car model with the catalog bellow.

Low Beam Headlight2000 H7
High Beam Headlight2000 H7
Front Fog Light2000 9006
Back Up Light2000 1156
Brake2000 1156
Dome Light2000 DE3423
Front Side Marker2000 12961
Front Turn Signal2000 P21W
License Plate2000 12844
Parking Light2000 194
Rear Side Marker2000 P21/4W
Rear Turn Signal2000 1156
Tail Light2000 P21/4W
Glove Box2000 DE3423
Stepwell2000 12844
Trunk2000 6411
Low Beam Headlight2000 D2S
High Beam Headlight2000 H7
Front Fog Light2000 9006
Back Up Light2000 1156
Brake2000 1156
Dome Light2000 DE3423
Front Side Marker2000 12961
Front Turn Signal2000 P21W
License Plate2000 12844
Parking Light2000 194
Rear Side Marker2000 P21/4W
Rear Turn Signal2000 P21W
Tail Light2000 P21/4W
Glove Box2000 DE3423
Stepwell2000 12844
Trunk2000 6411
Low Beam Headlight1999 – 2000, 2006 – 2011 H7
High Beam Headlight1999 – 2000, 2006 – 2011 H7
Front Fog Light1999 – 2000 9006
2006 – 2011 H11
Back Up Light1999 – 2000 1156
2006 – 2011 H21W
Brake1999 – 2000, 2006 – 2011 1156
Dome Light2006 – 2011 194
1999 – 2000 DE3423
Front Side Marker1999 – 2000, 2006 – 2011 12961
Front Turn Signal1999 – 2000 P21W
License Plate1999 – 2000, 2006 – 2011 12844
Parking Light2006 – 2011 12961
1999 – 2000 194
Rear Side Marker1999 – 2000 P21/4W
Rear Turn Signal1999 – 2000, 2006, 2009 – 2011 1156
2007 – 2008 P21W
Tail Light1999 – 2000 P21/4W
Front Inner Turn Signal2006 – 2011 PY21W
Front Outer Turn Signal2006 – 2011 12396NA
Courtesy2006 – 2011 12961
Glove Box1999 – 2000, 2006 – 2011 DE3423
Stepwell1999 – 2000 12844
Trunk1999 – 2000, 2006 – 2011 6411
Low Beam Headlight2006 – 2011 D1S
1999 – 2000 D2S
High Beam Headlight1999 – 2000, 2006 – 2011 H7
Front Fog Light1999 – 2000 9006
2006 – 2011 H11
Back Up Light1999 – 2000 1156
2006 – 2011 H21W
Brake1999 – 2000, 2006 – 2011 1156
Dome Light2006 – 2011 194
1999 – 2000 DE3423
Front Side Marker1999 – 2000, 2006 – 2011 12961
Front Turn Signal1999 – 2000 P21W
License Plate1999 – 2000, 2006 – 2011 12844
Parking Light2006 – 2009, 2011 12961
1999 – 2000, 2010 194
Rear Side Marker1999 – 2000 P21/4W
Rear Turn Signal1999 – 2000, 2007 – 2009, 2011 1156
2006, 2010 P21W
Tail Light1999 – 2000 P21/4W
Front Inner Turn Signal2006 – 2011 PY21W
Front Outer Turn Signal2006 – 2011 12396NA
Courtesy2006 – 2011 12961
Glove Box1999 – 2000, 2006 – 2011 DE3423
Stepwell1999 – 2000 12844
Trunk1999 – 2000, 2006 – 2011 6411
Low Beam Headlight1998 9006
High Beam Headlight1998 9005
Front Fog Light1998 H1
Back Up Light1998 1156
Brake1998 1157
Dome Light1998 578
Front Side Marker1998 P21/5W
License Plate1998 12844
Parking Light1998 12961
Rear Side Marker1998 1157
Rear Turn Signal1998 1156
Tail Light1998 1157
Front Inner Turn Signal1998 1157
Front Outer Turn Signal1998 12821
Center High Mount Stop Light1998 1156
Courtesy1998 6418
Glove Box1998 DE3423
Trunk1998 12844
Low Beam Headlight1998 – 1999 9006
High Beam Headlight1998 – 1999 9005
Front Fog Light1998 – 1999 H1
Back Up Light1998 – 1999 1156
Brake1998 – 1999 1157
Dome Light1998 578
1999 DE3423
Front Side Marker1998 – 1999 P21/5W
License Plate1998 – 1999 12844
Parking Light1998 – 1999 12961
Rear Side Marker1998 – 1999 1157
Rear Turn Signal1998 – 1999 1156
Tail Light1998 – 1999 1157
Front Inner Turn Signal1998 – 1999 1157
Front Outer Turn Signal1998 – 1999 12821
Center High Mount Stop Light1998 – 1999 1156
Courtesy1998 – 1999 6418
Glove Box1998 – 1999 DE3423
Trunk1998 – 1999 12844