What does pitch means in the context of the sizing of a breadboard?

Question

I am trying to build an eagle-cad part for an Arduino Micro. (so I can make a PCB and stick the arduino on it) I was hoping to derive the distance between the two rails of pins from the fact that on a 2.54 mm pitch breadboard, there are 5 holes in between.

Pin Empty Empty Empty Empty Empty Pin

Of course, it struck me that I don't really understand what the "pitch" is. Is it the distance between the outer-most parts of two holes, or the distance between the center of two holes? In other words, is the distance I am looking for 15.24 mm (2.54 * 6) or do I need to add something to account for the size of the holes?

Answer 1

The "pitch" is the center-to-center spacing of pins or holes. You may need to make accommodations for any "overhang" beyond the first or last pin/hole.

Answer 2

Like Ignacio said, pitch is the distance between the center of two holes. For a standard breadboard, that distance is 1/10 of an inch, or 100 mils. Look for parts like M08* in the Sparkfun library, for rows of pads designed for 100mil pitch headers, used for creating breadboard compatible parts. Also, a standard DIP's pins are 300mils wide. If you design a part that goes into a breadboard, it is convenient to space 2 rows of pins 300mils apart (or 400, 500, etc), so that the part can be placed across the center line of a breadboard.