Hi i am trying to make laminates with  carbon fibres using vacuum infusion process. i would like to know is there any calculations involved related to how must vacuum to be set for a given size of laminates to be produced

You need to be pulling as close to full vacuum as your equipment can produce with resin infusion

You might need to adjust the vacuum level if making parts via the wet-layed vacuum bagging process, so as not to make the laminate too dry.