A part that does not fit as modeled might still fit rotated
It is a common surprise late in a project: a part that looks fine in a 3D viewer turns out to be a few millimeters too long for the printer's bed in its default orientation, even though the same part would fit easily on its side. Before assuming a part needs to be scaled down or split into pieces, it is worth checking every practical axis-aligned rotation against the real build volume, since a 90-degree turn is free and often solves the problem outright.
How the check works
Every distinct axis-aligned rotation of the part's bounding box (up to six, fewer if some are duplicates) is checked against your build volume. If the part's current orientation already fits, that is confirmed directly. If not, every rotation that does fit is listed, so you can weigh a fit-enabling rotation against other orientation priorities like support burden or surface finish, covered by the Orientation Tradeoff Planner.
Worked example
A 240 x 90 x 60 mm part on a 220 x 220 x 250 mm build volume: the part does not fit as modeled (240 mm exceeds the 220 mm X axis), but rotating it so its 240 mm dimension runs along Z (which has 250 mm of headroom) clears the volume, and the tool returns that rotation as the best fit.
A common mistake
A frequent oversight is checking build volume fit against the part's raw bounding box while forgetting that a brim, raft, or skirt needs extra clearance around the part itself. A part that just barely fits at its exact dimensions can still fail to print if the adhesion aid you plan to use needs a few extra millimeters on every side that were never accounted for.
Limitations
This checks straight axis-aligned rotations of a simple rectangular bounding box against a simple rectangular build volume. It does not model a gantry-limited, dome-shaped, or otherwise non-rectangular printable envelope, and it does not account for the extra space a brim, raft, or skirt line needs; verify against your specific printer's real usable volume.