BenQ W3000 User Manual page 18

There is 5% tolerance among these numbers due to optical component variations. BenQ
recommends that if you intend to permanently install the projector, you should physically test
the projection size and distance using the actual projector before you permanently install it, so
as to make allowance for this projector's optical characteristics. This will help you determine
the exact mounting position so that it best suits your installation location.
18 Positioning your projector