Library Conventions | KiCad EDA

Version 3.0.43

Library maintainer rules & guidelines

F2.2 Footprint naming field prefixes

A footprint name has to convey a lot of information to clearly specify the purpose and parameters of the footprint. Some fields in footprint names are common to many footprints and can be shortened using special abbreviations.

Not all footprints will require the use of these abbreviations - they are provided as a method of standardising the manner in which footprint parameters are called out when encountered.

In many cases, the major dimensions (x/y/z) of a footprint may be specified without a prefix, as the body dimensions are assumed to have the greatest priority in the footprint name. Therefore, the "3.2x5.7mm" part of the example name below requires no 'B' prefix, and is not required to be written as "B3.2x5.7mm".

e.g. SOIC-8_3.2x5.7mm_P1.27mm

In cases where potential conflicts exist, however, the body dimensions must be explicitly named with the prefix B.

Refer to the table below for accepted prefix abbreviations.

Prefix Field Description Notes
B Body dimensions
  • Body size (XxYxZ)
  • Height parameter Z may be omitted
  • Prefix B may be omitted if the body size is the major dimension used to define the footprint
D Diameter
  • Diameter of major axis for cylindrical component
  • e.g. D10mm - 10mm diameter
H Height
  • Height of component measured from PCB
  • Body size B should be used in preference, where possible
  • e.g. H1.1mm - component measures 1.1mm above PCB
L Length
  • Length along major axis of component
  • Body size B should be used in preference, where possible
  • e.g. L15.3mm - 15mm length
O Offset
  • Offset, where no other name is more appropriate
  • For example, the distance between pads and the body. Affects silkscreen diagram.
  • e.g. O3.81mm - 3.81mm from pads to body.
W Width
  • Width along minor axis of component
  • Body size B should be used in preference, where possible
  • e.g. W4.75mm - 4.75mm width
EP Exposed pad dimensions
  • Packages that include a single exposed pad include the size of this pad. e.g. EP2.4x3.6mm - for a single 2.4mm x 3.6mm pad.
P Pad pitch
  • Pitch (distance) between pins, pads or leads
  • e.g. P0.63mm - 0.63mm pitch between pads
T Thickness Component thickness, where appropriate


  • LQFP-32_4x4x1.1mm_P1.65mm - LQFP package, 32 pins, 4x4mm body, 1.1mm height, 1.65mm pitch

  • CP_Radial_D4.5mm_P2.5mm_H10mm - Radial polarized capacitor, 4.5mm diameter, 2.5mm pitch, 10mm height

If the parameter is not found in the table above, the name of the parameter should be entered in full.

Following is a list of examples of (non-abbreviated) parameter names used in footprint naming

Prefix Field Description
Ball BGA Ball diameter
Clearance Clearance between pin rows
Drill Drill diameter
Layout Specific footprint layout
e.g. Layout3x7 for a BGA with 21 balls arranged in 3 columns and 7 rows
Lead Lead dimensions
Mask Custom soldermask dimensions
Pad Custom pad dimensions
Tab Tab dimensions