How much clearance should you include in through-hole components holes?

Is there a general rule as to how much clearance you should add to through-hole components' holes to allow them to fit easily? For example, if I have a component with 1mm pin diameter, what should the diameter of the holes for it's pads be?

PCB Assembly, PCB Design
December 13, 2023

0.1mm is too tight toward the high end if you’re designing for automatic insertion of parts with bent leads.
Usually 0.8mm is okay for most leads except fat diode leads, for which you can use 1.0mm.
Usually 1.3mm holes are specified for 1mm pins (for example on terminal block datasheets).
Sometimes 1.5mm which is really, really loose.

If the leads are flat or square rather than round, you can go a bit tighter on the diagonal dimension, assuming a round hole. For really flat leads, it’s better to specify a slot.

If you’re using some kind of special part, such as a staked connector or press-fit part, pay attention to the tolerances.

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.

Oliver Smith

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