Two projectors may publish similar throw ratios and still require different real installations. The manual and lens documentation control the usable zoom range, focus distance, image-size limits, reference point, ventilation, orientation, and approved mounting procedure.
Find the distance reference point
Throw distance is commonly measured from the lens to the image surface, not from the rear, front panel, mount plate, or wall. A ceiling mount may place its adjustment axis away from the lens. Translate the calculated lens position into body and bracket clearance only with the exact mechanical drawing.
Check zoom, focus, and image-size limits together
A calculated point can satisfy D ÷ W yet lie outside the model’s stated focus distance or image-size range. Interchangeable-lens projectors add lens-specific limits. Confirm that the desired combination appears inside every applicable range instead of relying on one ratio copied from a retailer table.
Lens shift and keystone do not replace placement checks
ThrowFit calculates horizontal size and distance only. It does not calculate vertical offset, lens-shift envelopes, keystone crop, optical-axis height, or obstruction clearance. Digital correction may reduce usable resolution and cannot prove that an extreme mounting position is supported.
Keep a pre-mount checklist
Record exact model and lens, firmware-relevant documentation date, usable image dimensions, ratio range, focus range, reference point, body depth, connector clearance, airflow, bracket adjustment, screen position, and measurement tolerance. Test the real projector temporarily whenever practical before making irreversible holes.