Boardsize and MountingHoles

Its maybe pritty simple to find
but i cand find it
WHERE is the Mounting Hole Zize and position for building a mountingPlate to Mount a arduino UNO on

i cand find any relatet mesurments
Mesuring myself with a scaler is pretty inacurate
and it seams the holes arent aligned like sqare so every hole is in XY not alogned to the other

Please Help

The board info pages have a drawing of the board in it. Yes, the locations of the holes are not particularly reasonable.

But it's not particularly relevant though, because the holes are mostly too close to other components to fit a screw head anyway! The full-size arduino boards in particular are really bad for mounting and integration into larger designs. A nano/pro mini mounted on prototyping board via pin headers is probably a much better choice.

There were some really poor decisions made for the board layout/dimensions back in the really early days, that got carried through for compatibility. I'm sure they never imagined how big arduino would become, or that decisions made in a hurry to meet planned production/shipping milestones would still be with us in 2020...

Also depends on which board in particular but plenty of people have taken quite precise measurements and posted them on thier sites etc.

Google is quite good at finding them. (UNO)

For the MEGA

For the mounting I found M2 to be better and able to pick up ALL the holes.
Use nylon standoffs here to avoid any contact issues.