MFDigital CD DVD Information Library
Thursday, June 10, 2004
CD Layout
The layout of the CD is shown in the diagram, including the Lead-in, Program & Lead-out areas with their start and end radii and other dimensions.

CDs measure 12cm in diameter with a 15mm diameter center hole. The audio or computer data is stored from radius 25mm (after the lead-in) to radius 58mm maximum where the lead-out starts.

All audio CDs are played at a constant linear velocity (CLV) of 1.3 m/s. The angular velocity (rpm) will reduce from the lead-in to the lead-out by a factor of 58/23 = 2.52.

This means that pits retain the same geometry wherever they are on the disc and there will be no change in performance across the disc.