Throw distance is the distance between the projector lens and the projection screen. It determines where the projector should be installed to produce the desired screen size.

Throw ratio describes the relationship between projection distance and image width. For example, a 1.2 throw ratio means the projector should be placed about 1.2 times the screen width away from the screen.

Projectors with zoom lenses usually support a throw ratio range. This means the same projector can create the same screen size from different installation distances.

This calculator is mainly for standard throw and short throw projectors. Ultra short throw projectors usually require model-specific placement data from the projector manufacturer.

Throw distance should be measured from the projector lens to the screen surface, not from the back or center of the projector body.