Clearances & Circulation
Will it fit? Measuring the delivery path
Furniture does not fail at the shop. It fails at the third turn, with two people holding it and nowhere to put it down.
On this page (8 sections)
Short answer
A rigid item passes an opening if the smaller of its depth and height, plus 1 in (2.5 cm) of margin, fits the clear width. It passes a right-angle corner between two corridors of width A only if its length is under about 2.83A minus twice its thickness. Where it fails in plan, tilting is the fix: tilt to angle F and the plan length falls to L x cos F while the height needed rises to L x sin F plus T x cos F.
The numbers, at a glance
- Margin to allow at every opening
- 1 to 2 in (2.5 to 5 cm)
- Clear width gained by removing door and stop
- about 2 in (5 cm)
- Clear width gained by removing architrave
- 0.75 in (2 cm) per side
- Corner turn, both corridors width A
- max length = 2.83A - 2T
- Turn into a side door, long items
- max length = W x (A - T) / T
- Free rotation in a corridor
- sqrt(L squared + T squared) less than corridor width
- Half-landing absolute bound
- sqrt(A squared + B squared + H squared)landing box diagonal
- Typical accessible lift car
- 68 x 51 in (173 x 130 cm), 36 in (91 cm) door
The four measurements#
Everything below is arithmetic on four numbers. Take them before you order, not after.
- The item. Length L, thickness T (the smallest of its three dimensions once the feet are off), and the depth and height of its end profile. Manufacturers list depth at the widest point of the arm; check whether that includes the cushion.
- Every opening. Clear width and clear height, measured with the door standing open at 90 degrees, from the face of the leaf to the stop on the far jamb. This is roughly 2 in (5 cm) less than the nominal door size, as explained in door sizes, swings and the space they need.
- Every turn. The width of the space on both sides of the corner, measured to the finished surfaces including skirting and radiators. Also the width of any half-landing on a stair.
- The lowest overhead point. Ceiling height along the route, and specifically the underside of stair bulkheads, door heads, pendant lights and beams. This is the number that decides whether you can tilt, and tilting is the move that rescues most deliveries.
Rule one: the straight-through test#
An item goes through an opening if two of its three dimensions fit. Since almost everything is longer than it is deep or tall, the test is:
A sofa 88 in long, 38 in deep, 34 in high with 5 in feet: take the feet off and the end profile is 38 x 29 in. The controlling number is 29 in (74 cm), so a 32 in (81 cm) door giving 30 in clear passes it, tightly, on its side.
Rule two: the diagonal test#
The diagonal of the end profile is sqrt(depth squared + height squared). For that 38 x 29 in sofa: sqrt(1444 + 841) = sqrt(2285) = 47.8 in (121 cm).
If the diagonal is less than the clear width, the item can be presented to the opening at any angle and will pass. If the diagonal is greater than the clear width, as here, it only fits in one orientation, and that changes the problem: you now need enough space in front of the opening to get it into that orientation before it arrives. A head-on approach from outside a front door is fine. A doorway at the end of a 36 in (91 cm) hall is not.
This is why the diagonal matters even though it is never the dimension that physically passes through the frame. It tells you whether orientation is free or forced.
Rule three: corners#
For a right-angle turn between two corridors of equal width A, with an item of thickness T:
The 2.83 is 2 x sqrt(2), and it falls out of the geometry of a line pivoting past the inner corner: the classic result for a thin rod is (A^(2/3) + B^(2/3))^(3/2), which for A = B reduces to 2.83A. The minus 2T term is the penalty for real thickness, and it is brutal. Every inch of depth costs two inches of allowable length. That single sentence explains most delivery failures.
A separate case is a long item turning out of a corridor into a door in its side wall. Here the item has to be angled enough to fit the door's clear width W before any of it can cross the wall plane, and while it is at that angle its tail is still swinging in the corridor:
Rule four: tilting, and why it saves the day#
Everything above is plan geometry, which assumes the item stays flat. It rarely does. Tilt an item to an angle F from horizontal and its plan footprint shrinks while its vertical demand grows:
- Plan length = L x cos F
- Height needed = L x sin F + T x cos F
For an 88 in (224 cm) sofa carcass 29 in (74 cm) thick:
| Tilt | Plan length | Height needed | Fits under 96 in ceiling? |
|---|---|---|---|
| 0 degrees (flat) | 88 in (224 cm) | 29 in (74 cm) | yes |
| 30 degrees | 76 in (193 cm) | 69 in (175 cm) | yes |
| 45 degrees | 62 in (157 cm) | 83 in (211 cm) | yes |
| 60 degrees | 44 in (112 cm) | 91 in (231 cm) | only just |
| 75 degrees | 23 in (58 cm) | 93 in (236 cm) | only just |
| 90 degrees (on end) | 29 in footprint | 88 in (224 cm) | yes, if nothing hangs |
Read the table as a currency exchange. At 60 degrees you have converted 44 in of plan length into 62 in of height, which is exactly the trade you want at a corner. The limit is not the ceiling itself but the lowest thing hanging from it: a pendant, a smoke alarm, a ceiling rose. Deduct 4 in (10 cm) from the ceiling height before using this table.
The worked example#
Stairs and lifts#
On a stair, three things bind. The clear width between handrails, which is the stair width less up to 4.5 in (11 cm) per rail. The headroom over the pitch line, which under IRC R311.7.2 is at least 6 ft 8 in (2032 mm) but is often less over a bulkhead. And the landing box, which is the real killer, because a turn on a half-landing is a 180 degree rotation in a space rarely larger than 36 x 36 in (91 x 91 cm). Straight flights with no turn will take almost anything the doors will take. See stair dimensions for the geometry.
In a lift, the door is the constraint, not the car. The ADA elevator car in Table 407.4.1 pairs a 36 in (91 cm) side-opening door with a car about 68 in (173 cm) wide and 51 in (130 cm) deep, and a BS EN 81-70 Type 1 accessible car is 1000 x 1250 mm (39 x 49 in) with an 800 mm (31.5 in) door. The car's space diagonal is large, often 10 ft (3 m) or more with an 84 in (213 cm) ceiling, so an item that gets through the doors can nearly always be stood up inside. Measure the door, and measure the lobby in front of it: you cannot angle an item into a lift you cannot angle it in front of.
Buying yourself inches#
Ranked by how much they give per minute of work:
| Action | Gain | Effort |
|---|---|---|
| Take the door off its hinges | 1.5 in (4 cm) | 5 minutes |
| Prise off the door stop | 0.5 in (1.3 cm) | 10 minutes |
| Remove the architrave, one side | 0.75 in (2 cm) | 15 minutes, redecoration |
| Remove sofa feet | 4 to 6 in (10 to 15 cm) of height | 10 minutes |
| Unbolt sofa back and arms | reduces thickness to 10 to 14 in (25 to 36 cm) | 30 minutes, if designed for it |
| Remove handrail and brackets | 3.5 to 4.5 in (9 to 11 cm) | 30 minutes, redecoration |
| Remove newel post | 4 to 6 in (10 to 15 cm) at the landing | structural, get advice |
| Remove a casement sash for a hoist | full window opening | specialist |
The five minute check#
Cut a piece of cardboard to the item's end profile, depth by height with the feet off. Carry it along the route holding it upright. Where it will not pass, you have found your constraint in the time it takes to walk. Then measure that one point properly, apply the formulas above, and decide between a smaller item, a knock-down frame and a hoist before you pay a deposit. Sofa dimensions to check against your room, rather than your route, are in seating layout dimensions.
Frequently asked questions#
How do I know if a sofa will fit through my door?
Take the sofa's depth and its height with the feet removed. The smaller of the two must be at least 1 in (2.5 cm) less than the door's clear width, because the sofa goes through on its side. A 36 in (91 cm) deep, 29 in (74 cm) high sofa needs 30 in (76 cm) of clear width, which a 32 in (81 cm) leaf provides once the door itself is taken off its hinges.
What is the diagonal trick for measuring furniture?
Calculate sqrt(height squared + depth squared) for the end profile of the piece. If that diagonal is less than the clear width of the opening, the item can be presented at any angle and will pass regardless of approach. If it is greater, the item only fits in one specific orientation, which means the approach in front of the opening has to allow you to get it into that orientation first.
How do I calculate whether something turns a corner?
For two corridors of equal width A and an item of thickness T, the longest item that can turn the right-angle corner is about 2.83 x A minus 2 x T. In a 36 in (91 cm) corner, a 12 in (30 cm) deep bookcase maxes out around 78 in (198 cm) and a 24 in (61 cm) deep wardrobe around 54 in (137 cm). Each extra inch of thickness costs two inches of length.
What four measurements should I take before a delivery?
One: the item's length, depth, height and end diagonal. Two: the clear width and clear height of every opening on the route, measured with the door open at 90 degrees. Three: the width of the space on both sides of every turn. Four: the lowest overhead point anywhere on the route, including stair bulkheads and pendant lights.
Does removing the banister help?
Yes, more than most people expect. A handrail and its brackets project 3.5 to 4.5 in (9 to 11 cm) from the wall at exactly the height where you carry things, and a newel post at the head or foot of a flight takes 4 to 6 in (10 to 15 cm) out of the landing. Removing both can convert a 36 in (91 cm) stair into a genuine 40 in (102 cm) one for a day.
When should I order knock-down furniture instead?
When the item fails a turn even after tilting, or when the largest single piece after disassembly is more than about 12 in (30 cm) thick. Thickness is what kills a corner, so a knock-down frame that reduces a 29 in (74 cm) thick sofa carcass to a 12 in (30 cm) panel typically converts an impossible route into an easy one.
Can I hoist furniture through a window?
It is a normal professional service, priced per item, and it is often cheaper than the alternative. It needs a window or balcony opening larger than the item's cross-section, an obstruction-free face to the building, and permission from anyone who controls the ground below. Casement sashes usually come out in minutes, which is what makes the opening large enough.
Sources and standards referenced#
- 2010 ADA Standards for Accessible Design US Department of Justice404.2.3 door clear width, 407.4.1 elevator car dimensions
- International Residential Code (IRC) 2021 International Code CouncilR311.6 hallway width, R311.7 stair width, landings and headroom
- BS EN 81-70, Safety rules for the construction and installation of lifts. Accessibility to lifts for persons including persons with disability British Standards Institutionminimum accessible lift car sizes
- Architects' Data Ernst Neufert, Wiley-Blackwellcorridor turning geometry and lift car dimensions
- Human Dimension and Interior Space Panero and Zelnik, Whitney Library of Designcarrying clearances and furniture envelope dimensions
We cite published codes, industry planning guidelines and manufacturer specifications. Where a figure is our own recommendation rather than a published standard, the text says so. See how we measure.