I'm making the footprint of a component (this one, in particular) but I'm stuck with the measures which the "datasheet" specify, since I'm not familiar with this notation.

enter image description here

enter image description here

I've seen this kind of notation in several datasheets (not only connectors), and I always have the same question when it's time to make the footprint. Can anyone give me a hand?

what means that symbol?

PS: I know that the second Image is not needed for the footprint, but is always good to know what it is representing

  • 3
    \$\begingroup\$ 1.58 is millimeters. 0.062 is inches (or 62 mils). You probably know that the circle with a line through it means "diameter" and that +/- specifies a tolerance range. \$\endgroup\$
    – Kaz
    Commented Aug 20, 2014 at 20:58

2 Answers 2


The item you copied into your 2nd image is a diameter, dual dimensioned and toleranced in mm and inches, as others have explained.

This is mainly what you need to worry about- the footprint specification.

For completeness (and because I think you were asking about it) this- enter image description here

Is the positional tolerance of the pins given using the GD&T standard.

The first character is a symbol ⌖ indicating that it is "positional tolerance" that is being specified.

The 0.50/0.02 is the tolerance in dual units (mm and in inches).

U is the primary datum reference plane (the bottom face of the plastic).

X or Y is the secondary datum reference.

If pegs are present, the pin location tolerance is relative to the peg on the opposite end (-X-), and if they are not present, the tolerance is relative to the locations pin on the opposite end (-Y-).


Most of the time, measurements in datasheets are given in millimeters(mm) although most manufacturers will also include the inches measurement as well.

In this case, your top measurement is in mm and can have a variation of +- .05mm depending on the actual piece you have. The bottom measurement is in inches and will have a variation of +- .002"


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