Will a chair (122x97x76 cm) Fit Up 91 cm Stairs?

−12 in over

· ON THE WIDTH AXIS

It exceeds the opening at the tightest point.

Your chair will not fit through the stairway — and it is clearly over the limit at the tightest point.

4 ft vs 3 ft

Overage −12 in (−33.3%) on the WIDTH axis

AStair slope angle✓ PASS

\theta_{\text{slope}} = \operatorname{atan2}(\text{riser}, \text{tread})

↓ SUBSTITUTE

\operatorname{atan2}(7.5, 10)

Plain English: Slope of the stair run from riser-over-tread geometry.

BTilted carry envelope✓ PASS

h_{\text{eff}}(\theta) = \text{vert}\cos\theta + \text{along}\sin\theta

↓ SUBSTITUTE

38\cos(37^\circ) + 48\sin(37^\circ)

Plain English: Vertical envelope of a tilted item being carried up stairs.

CAxis inequality · stair width✕ FAIL

d_{\text{item}} \;\le\; d_{\text{space}}

↓ SUBSTITUTE

30 \;\overset{?}{\le}\; 28.1\quad(\text{stair width})

↓ EVALUATE

30\,\text{in} \;>\; 28.1\,\text{in} \;\Longrightarrow\; \Delta = -1.9\,\text{in}

Plain English: Along the stair width, the item is 30 in and the space allows 28.1 in — over by 1.9 in.

DDiagonal clearance · Pythagorean✓ PASS

\sqrt{a^2 + b^2} \;\le\; \sqrt{a_{\text{sp}}^2 + b_{\text{sp}}^2}

↓ SUBSTITUTE

\sqrt{30^2 + 38^2} \;\overset{?}{\le}\; \sqrt{28.1^2 + 80^2}

↓ EVALUATE

48.4\,\text{in} \;\le\; 84.8\,\text{in} \;\Longrightarrow\; \Delta = +36.4\,\text{in}

Plain English: Tilted corner-to-corner the face spans 48.4 in, inside the opening's 84.8 in diagonal — but a tilt only buys diagonal room, it can't widen the throat.

E3D space diagonal✓ PASS

\mathcal{D}_{3D} = \sqrt{L^2 + W^2 + H^2}

↓ SUBSTITUTE

\sqrt{48^2 + 30^2 + 38^2}

↓ EVALUATE

68.1\,\text{in} \;\le\; 84.8\,\text{in} \;\Longrightarrow\; \Delta = +16.7\,\text{in}

Plain English: Corner to corner the item reaches 68.1 in — keep that swing room in mind for the turn after.

FMinimum required space · stair width✕ FAIL

d_{\text{req}} = d_{\text{item}} + t

↓ SUBSTITUTE

30 + 2 = 32

Plain English: Smallest space on the limiting axis that would admit this item (with handling tolerance).

GLargest item that fits · stair width✕ FAIL

d_{\max} = d_{\text{space}} - t

↓ SUBSTITUTE

28.1 - 2 = 26.1

Plain English: Largest item dimension this space admits on the limiting axis (after handling tolerance).

Orientation	Width	Height	Result
upright front-first	—	—	✕
upright side-first	—	—	✕
on side, front-first	—	—	✕
on side, side-first	—	—	✕
laid flat, depth across	—	—	✕
laid flat, height across	—	—	✕

How the stair-passage check works

Stairs care about ceiling clearance on the incline plus stair-width clearance for the carrying motion; treat the item’s diagonal as the effective length.

Use the standard residential stair geometry: 7 in rise per step, 11 in run, ~37° incline.
Project the item’s diagonal across the incline to get the effective length the stairwell must clear.
Apply the ceiling-clearance constraint to the carry pose (item tilted along the incline).
Apply the stair-width constraint to the item’s narrow cross-section so movers can step alongside.
Verdict ladder (verdict-tiers.js, shared with door): FITS ≥ 2 in; FITS_TIGHT 0.5–2 in; FITS_VERY_TIGHT 0–0.5 in; DOESN'T_FIT below.

Tread / rise / incline use ASTM-style residential averages (7 in rise, 11 in run, ~37° pitch); commercial stairwells differ.

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Will a chair (122x97x76 cm) fit up 91 cm stairs?

Expert analysis

It exceeds the opening at the tightest point.

Dimensions

Space geometry

Handling

Similar calculations

Run your own fit check