It appears that there is an error in the conversion between Inch, mil, and mm dimensions in EasyEDA. Noting that the conversion factor was standardised in 1959 at 1inch = 2.540mm, errors in the third decimal place should be avoidable if arithmetic precision is suitably matched to the number of decimal places displayed, and appropriate rounding is used. Are all calculations done in mil regardless of the unit of measure selected and converted afterwards, or are calculations done, as they should be, in the selected unit of measure? This may be related to my [previous post on DRC errors.](https://easyeda.com/forum/topic/DRC-Check-Errors-6bd200ba0ce34afaa0cd58488311457e) When checking the Gerber PTH Drill sizes with Gerbv for my board I found that I had nearly twice as many drill sizes as hole sizes. I therefore went back to the board schematic and reviewed/ modified all the PCB footprints (PCB Lib) and standardised on hole/pad sizes based loosely upon IPC recommendations for lead clearance and relative pad size. This resulted in 6 different hole sizes being used: 0.800mm, 0.899mm, 1.000mm, 1.100mm, 1.200mm and 1.300mm. Note the 0.899mm is the size used for AXIAL-0.3 from EELib which i have used for all resistors, so I used the same sized hole (0.899mm) for all components needing 0.9mm. However, the resulting Gerber shows additional drill size requirements of 1.101mm for some of the 1.100mm, 1.201mm for some of the 1.200mm and 1.301mm for all of the 1.300mm holes. Going back and editing the footprint files to ensure that holes were defined to 3 decimal places (i.e. type 1.300 instead of 1.3) eliminated the 1.201mm and 1.301mm extraneous Gerber drill sizes, but NOT the 1.101mm. Checking all the 1.1mm holes on the EasyEDA PCB view showed them all indeed to be 1.100mm, however the same board in Gerbv has them all as 1.101mm. It is interesting to note that the holes from AXIAL-0.3 and others set to 0.899mm in order to standardise all come out at the preferred diameter in Gerber as 0.900mm.