Can a Bed Frame Fit Through a Doorway?
How to choose among the six axis-aligned poses for a flat, often disassembled bed frame, why a wrong pose produces a huge negative remainder, and what the joint doorway-plus-room pose matrix actually proves.
- Published
- Updated
- Calculation version
- 2.0.0
- Maintenance
- These pages are maintained together with the calculation engine in this repository. A change to the geometry or verdict logic requires the published method statement and its automated checks to be updated in the same change. There is no separately credited editorial team and no external reviewer.
The question
For a flat, often disassembled bed frame, which of the six axis-aligned poses should be used, and why is a continuous tilt not part of the calculation?
Short answer
First decide what object you are moving: an assembled frame or a set of flat panels. Then enter its outer extents as one box and let the engine test the six axis-aligned poses against both the doorway section and the room volume. A pose that points the long edge at the opening can fail badly while another pose succeeds, so the result is a conditional verdict with a recommended pose. Continuous tilt is deliberately not searched: version one only evaluates six poses built from 3×3 rotation matrices, and it states that limitation rather than pretending to have found the optimum.
Why this happens
A flat frame is still one box
A bed frame is wide, long and shallow. Upright, it presents its full width to the doorway; lengthwise, it may present its full length. Because the three extents differ a lot, pose selection changes the answer more dramatically here than for a nearly cubic object.
If the frame is disassembled into panels, each panel is a different, much smaller box. The tool has no parts list: you must enter the largest panel you will actually carry, not the assembled bed.
Six poses, not an angle sweep
Each tested pose is a real rotation matrix R = Rz · Ry · Rx. The bounding box is |R| · h, so for ninety-degree rotations the three extents are simply permuted. There is no search over arbitrary angles and no interpolation between poses.
This is declared as AXIS_ALIGNED_POSES_ONLY. A real mover may succeed with a diagonal tilt that the tool never tries; equally, a promising-looking conditional result is not a guarantee that the physical move will work.
Why one shared pose matters
The engine evaluates the doorway section and the room volume for every pose, then builds a joint matrix recording which poses satisfy both. A pose that clears the door but cannot fit the room is not a solution.
When the currently selected pose fails but another tested pose satisfies both checks, the verdict is CONDITIONAL with a REQUIRES_POSE_CHANGE reason. That is a precise statement about the data, not a vague warning.
Step by step
- 01
Decide: assembled frame or flat panels
Measure the largest single item that will actually cross the doorway. If the frame breaks down, use the biggest panel’s extents, not the dimensions of the made-up bed.
- 02
Record the three extents on the object’s own axes
Length, width, height in one unit. For a flat-packed frame the thickness is usually the smallest number, and it is often the one that becomes the projected width in a useful pose.
- 03
Measure the doorway and the room
Smallest of three clear-width readings, lowest head height, and the rectangular room volume. Leave frame depth blank if you genuinely cannot measure it; the engine will say so.
- 04
Compare poses and read the joint result
Start with any pose, note the remaining values, then apply the recommended pose. Check whether the reasons list names a required pose change, a missing frame depth, or no single pose that fits both.
Worked example: what a wrong pose looks like
A flat-packed frame bundle measures 2000 mm long, 1500 mm wide and 300 mm thick. The doorway clears 800 mm by 2050 mm with a 180 mm frame; the room is 3000 × 4000 × 2600 mm. The LENGTHWISE pose is deliberately selected and no extra clearance is requested. These are inputs. The table below is the engine’s live output, including the recommended pose.
Input data
| Item | Flat-packed bed frame |
|---|---|
| Length | 2000 mm |
| Width | 1500 mm |
| Height | 300 mm |
| Clear width | 800 mm |
| Clear height | 2050 mm |
| Frame depth | 180 mm |
| Room width | 3000 mm |
| Room length | 4000 mm |
| Room height | 2600 mm |
| Extra clearance | 0 mm |
| Selected pose | Lengthwise |
Calculation process
- 01In the lengthwise pose the long 2000 mm extent is presented to the 800 mm clear opening. That is a deliberately poor choice, and the resulting width comparison is strongly negative — the number in the table below is the engine’s own, not a value written into this article.
- 02The engine does not conclude from one bad pose. It evaluates all six permutations for the doorway section and for the room volume, then asks whether any single pose satisfies both.
- 03When another pose works, the verdict is conditional and the reasons list names the required pose change; the recommended pose comes from the joint matrix. That distinction is the whole point of this example: a large negative remainder for ONE pose is not a verdict on the object.
Engine result, computed live
Every value in this table is produced at render time by the same engine that powers the calculator. The article supplies inputs only.
- Overall status
- CONDITIONAL
The geometry is not definitively clear. A local check needs a different posture, a blocking limitation applies, or no single posture satisfies both checks.
- Recommended pose
- Upright · quarter turn
| Comparison | Required | Available | Remaining |
|---|---|---|---|
| Doorway clear width | 2000 | 800 | -1200 |
| Doorway clear height | 300 | 2050 | 1750 |
| Room width | 2000 | 3000 | 1000 |
| Room length | 1500 | 4000 | 2500 |
| Room height | 300 | 2600 | 2300 |
- DOORWAY_REQUIRES_POSE_CHANGE
- ROOM_FIT_PASS
Calculation version 2.0.0
Applicable range
One rectangular box (assembled frame or one largest panel), one straight doorway section, six axis-aligned poses and a rectangular room volume.
Limits of this example
- No continuous tilt search; a diagonal solution is neither tested nor excluded.
- A disassembled set of panels is not modelled as separate objects. Enter the largest single item you will carry.
- Frame-depth rotation, door leaves, skirting and the moving route are not modelled.
- A zero remainder counts as touching rather than a collision; real handling needs a margin.
Formulas used
Pose to bounding box
h_box(pose) = |R_pose| · (L, W, H)
Six explicit 3×3 matrices; for axis-aligned rotations the result is a permutation of the three extents.
Joint feasibility
feasible(pose) = passesSection(pose) AND fitsRoom(pose)
The engine records this for all six poses and reports hasJointlyFittingOrientation.
Verdict when the selected pose fails
selected fails AND ∃ feasible pose → CONDITIONAL (REQUIRES_POSE_CHANGE)
The status is produced by the engine and rendered as-is; the UI never rebuilds it.
Scope and limits
- AXIS_ALIGNED_POSES_ONLY — exactly six poses, no arbitrary angle.
- BOUNDING_BOX_ONLY — one box per item, not a parts list.
- SECTION_ONLY for the doorway, STATIC_VOLUME_ONLY for the room; PATH_NOT_MODELLED.
- Door leaves, obstacles and frame-depth rotation are not modelled.
- Invalid input returns a structured INVALID_INPUT failure rather than a geometric guess.
Common mistakes
Entering the assembled bed when you will carry panels
The assembled bed is much larger than any single panel. The tool models one box, so it would describe an object that never crosses the doorway.
Judging the object by one bad pose
A strongly negative remainder belongs to the SELECTED pose. Read the recommended pose and the reasons list before deciding.
Reading CONDITIONAL as an error message
Here it usually means a pose change is required while another tested pose satisfies both checks. That is useful information, not a failure of the tool.
Assuming the tool found the best physical angle
It searched six axis-aligned permutations only. No claim is made about diagonal tilts, and the limitation is shown in the result.
Run the fit calculator
Enter the largest item you will actually carry, then use the calculator to step through poses. The comparison table, the reasons list and the recommended pose all come from the same engine pass, so you can see exactly why one orientation fails and another satisfies both checks.
Enter your own furniture, doorway and room dimensions to see the same comparisons for a real case.
Open the calculator