Through Hole Sizes for Leaded Parts

What should the hole size be for a leaded through hole component ?

Factors to consider include:

Max lead size.
Min Hole size.
Solder flow through the lead.

Typically the finished hole size should be 8 to 10 mils larger than the maximum lead diameter.

Example:

If the component has a round lead with a diameter of 32 mils: 

Then the finished hole diameter should be 32 + 10 = 42 mils.

Note for square and rectangular shaped leads the lead diameter needs to account for the diagonal dimension of the lead.

Drilled holes in the PCB - Metric

Metric guidance lines for drill holes

Drilled holes in the PCB | Eurocircuits:

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