BOLT CIRCLE DIAMETER CONSTANTS This is a handy chart for the occasional bolt circle that saves having to set up a rotary table or spacer to do it. Just multiply the constants in the chart by the diameter of the bolt circle you want to create to get the appropriate X and Y dimensions. Click on the image to download a PDF file, laminate it and keep it handy in the shop. Mine is stuck to a filing cabinet with a magnet for easy access.