How to use the furniture doorway clearance calculator
- Enter the width, depth and height of the piece, with legs, feet or cushions left on unless you can remove them.
- Enter the doorway clear width and height, measured where you can actually carry the piece through, with the door open as far as it goes or off its hinges.
- Optionally enter the widths of two hallways that meet at a right angle. In the advanced option, set the room to spare on each side.
- Read the result for each way of carrying the piece, and for turning the corner. The tilt angle tells you how far to turn the piece.
Formula
a p by q rectangle (p at least q) fits an a by b opening (a at least b) if p <= a and q <= b, or if q <= b and b >= (2 p q a + (p^2 - q^2) x sqrt(p^2 + q^2 - a^2)) / (p^2 + q^2)
smallest tilt = atan(q / p) + acos(a / sqrt(p^2 + q^2))
longest rectangle of width q round a corner = minimum over t of (w1 - q cos t) / sin t + (w2 - q sin t) / cos t, for t from 0 to 90 degrees
The first rule treats the piece as seen from the front as it goes through the doorway. The corner rule treats it as seen from above in two hallways of widths w1 and w2.
A sofa and a dresser
A sofa 84 inches wide, 36 deep and 34 high cannot go through a doorway 30 inches wide and 80 high with 1 inch to spare on each side: the opening is 28 by 79 inches, and every cross-section of the sofa has a side longer than 28 inches. A dresser 60 wide, 20 deep and 34 high goes through width first, since its 20 by 34 inch cross-section fits the opening as it is.
Around a turn between hallways 42 and 36 inches wide (40 and 34 after the room to spare), a piece 20 inches wide can be 64.4 inches long, so the 60 inch dresser turns the corner. A cross-section of 41 by 8 inches into an opening of 40 by 30 inches does fit, if tilted by 27.8 degrees.
What the check does
Carrying a piece through a door is a rectangle passing through a rectangle: you look at the piece end-on and ask whether its cross-section can be turned to fit the opening. Turning a long thin shape lets it pass through an opening that is smaller than its length in every straight orientation. The calculation finds the smallest turn that works, so you know how far to tilt.
The page checks three ways of carrying: the depth first, the width first, and the height first (on its end). Only the first two are used for the corner, because turning a corner with a piece on its end depends on how the piece is held.
What it cannot see
This is a flat, two-dimensional check. It does not account for door frames and hinges that stick out, light switches, stair turns, the ceiling height while you tilt a tall piece, or whether the piece can flex or come apart. Measure twice, remove legs, cushions and doors where you can, and get help for heavy loads. For the truck and the boxes, see the moving truck size calculator and the moving boxes calculator; for frames and openings, the rough opening calculator; for how many people fit in a room, the room capacity calculator.
Assumptions and limits
- The piece is a rigid box and the opening is a rectangle. Rounded corners, sloped shapes and arms that stick out are ignored.
- The room to spare is taken off both sides of the doorway width and off the top of the height, and off both sides of each hallway.
- The corner check is for a right-angle turn between two straight hallways of constant width, with the piece held level.
- All dimensions use one unit, inches or centimeters.
Frequently asked questions
Why can a piece fit although it is longer than the door?
A rectangle that is too long to pass straight can pass at an angle, because the diagonal of an opening is longer than its sides. The tilt angle says how far to turn it. The condition is exact for a flat rectangle.
How do I measure a doorway?
Measure the narrowest gap that you can carry the piece through. With the door open, the stop and the hinges reduce the width, so many people take the door off its hinges and measure the frame side to side.
Does the corner check include a door at the turn?
No. It assumes two plain hallways. A door or a landing in the turn changes the room you have, so measure the real space.
What is room to spare?
It is clearance for hands, knuckles and scrapes. One inch on each side is an example. A tight fit may be possible on paper and a struggle in practice.