Murphy Bed Size Calculator
Cabinet width, height and depth for a wall bed, how far it swings into the room, and whether it clears your ceiling, your wall and your light fitting. Drag the bed open and watch the clearances change.
Enter your values
Results update instantly as you type.
Everything is worked out in your browser, so the numbers never leave your device.
Results
Working
- cabinet depth = back 0.5 in + deck 1.5 in + mattress 10 in + gap 1 in + face 0.8 in = 13.8 in, up to 14 in
- cabinet width = 80 in mattress + 2 x 1 in clearance + 2 x 0.8 in carcass + 2 x 1.5 in mechanism = 86.5 in, up to 86.5 in
- cabinet height = pivot 5.5 in + 60 in mattress + 2 in head + 0.8 in carcass = 68.3 in, up to 68.5 in
- ceiling needed = 68.5 in + 0 in crown + 1 in scribe = 69.5 in
- deck arm = 60 in + 2 in foot rail = 62 in
- projection = 14 in cabinet + 62 in arm = 76 in
- swing radius = sqrt(62 in^2 + 11.5 in^2) = 63.1 in
- room depth needed = 76 in + 30 in walkway = 106.8 in
- sleep height = pivot 5.5 in + deck 1.5 in + mattress 10 in = 17 in
See it in the room
Drag the opening slider to watch the bed swing. The dashed line is the envelope it sweeps, which is what a chest of drawers or a low pendant has to clear.
Quick answer
A Murphy bed cabinet is the mattress plus a fixed set of allowances: about 3.8 in of depth on top of the mattress thickness, 3.5 in on the width, and 8.3 in on the height. A vertical queen therefore lands near 63.5 in wide, 88.5 in tall and 14 in deep, and reaches 96 in into the room when open.
depth = mattress + 3.75 in; height = mattress length + 8.25 in; projection = depth + mattress length + 2 in
Worked example
A queen mattress, 10 in thick, in a room with an 8 ft ceiling, 96 in of clear wall and 144 in of depth.
| Cabinet, vertical | 63.5 in wide x 88.5 in tall x 14 in deep |
|---|---|
| Ceiling needed | 89.5 in, leaving 6.5 in |
| Projection when open | 96 in |
| Widest point of the swing | 97 in, which is 1 in past where it lands |
| Room depth needed | 126.8 in with a 30 in walkway |
| Sleep surface height | 17 in |
| Assembled weight | 374 lb, heavy lift kit |
| Same mattress, horizontal | 86.5 in wide x 68.5 in tall, projecting 76 in |
Fits, with something to watch. The number that catches people out is the projection: 96 in is most of a small bedroom gone the moment the bed comes down. Turning the same mattress on its side drops that to 76 in and the cabinet to 68.5 in tall, but it then wants 86.5 in of wall instead of 63.5 in. In this room both work, so it comes down to which wall you can spare.
Working
- cabinet depth = back 0.5 in + deck 1.5 in + mattress 10 in + gap 1 in + face 0.8 in = 13.8 in, up to 14 in
- cabinet width = 60 in mattress + 2 x 1 in clearance + 2 x 0.8 in carcass = 63.5 in, up to 63.5 in
- cabinet height = pivot 5.5 in + 80 in mattress + 2 in head + 0.8 in carcass = 88.3 in, up to 88.5 in
- ceiling needed = 88.5 in + 0 in crown + 1 in scribe = 89.5 in
- deck arm = 80 in + 2 in foot rail = 82 in
- projection = 14 in cabinet + 82 in arm = 96 in
- swing radius = sqrt(82 in^2 + 11.5 in^2) = 82.8 in
- room depth needed = 96 in + 30 in walkway = 126.8 in
- sleep height = pivot 5.5 in + deck 1.5 in + mattress 10 in = 17 in
Murphy bed cabinet size by mattress
Minimum cabinet dimensions for a 10 in mattress, both ways round. Vertical folds up along the length of the mattress and needs the ceiling; horizontal folds up along the width and needs the wall. Depth is the same either way, because it is set by the mattress thickness.
| Mattress | Size | Vertical W x H | Projection | Horizontal W x H | Projection | Depth |
|---|---|---|---|---|---|---|
| Twin US | 38 in x 75 in | 41.5 in x 83.5 in | 91 in | 81.5 in x 46.5 in | 54 in | 14 in |
| Twin XL US | 38 in x 80 in | 41.5 in x 88.5 in | 96 in | 86.5 in x 46.5 in | 54 in | 14 in |
| Full / Double US | 54 in x 75 in | 57.5 in x 83.5 in | 91 in | 81.5 in x 62.5 in | 70 in | 14 in |
| Queen US | 60 in x 80 in | 63.5 in x 88.5 in | 96 in | 86.5 in x 68.5 in | 76 in | 14 in |
| King US | 76 in x 80 in | 79.5 in x 88.5 in | 96 in | 86.5 in x 84.5 in | 92 in | 14 in |
| Single, 3'0" UK | 36 in x 75 in | 39.5 in x 83.5 in | 91 in | 81.5 in x 44.5 in | 52 in | 14 in |
| Double, 4'6" UK | 54 in x 75 in | 57.5 in x 83.5 in | 91 in | 81.5 in x 62.5 in | 70 in | 14 in |
| King, 5'0" UK | 60 in x 78 in | 63.5 in x 86.5 in | 94 in | 84.5 in x 68.5 in | 76 in | 14 in |
| 140 x 200 cm EU | 55.1 in x 78.7 in | 59 in x 87 in | 95 in | 85.5 in x 63.5 in | 71.5 in | 14 in |
| 160 x 200 cm EU | 63 in x 78.7 in | 66.5 in x 87 in | 95 in | 85.5 in x 71.5 in | 79 in | 14 in |
Projection is measured from the wall to the foot of the open bed. Add a walkway on top of it before deciding the room is deep enough.
Ceiling light clearance over a wall bed
The bed sweeps a quarter circle on its way down, and the top corner travels on the diagonal of the bed box. The lowest a pendant or fan can hang, at a given distance from the wall, is the height of that arc plus the pivot.
| Bed | 24 in out | 36 in out | 48 in out | 60 in out | 72 in out | 84 in out |
|---|---|---|---|---|---|---|
| Twin, vertical | 83 in | 80.5 in | 76 in | 68.5 in | 57.5 in | 40 in |
| Full, vertical | 83 in | 80.5 in | 76 in | 68.5 in | 57.5 in | 40 in |
| Queen, vertical | 88 in | 85.5 in | 81 in | 74.5 in | 65 in | 50 in |
| Queen, horizontal | 68 in | 65 in | 59 in | 49 in | 30.5 in | 5.5 in |
Read the column for how far your fitting sits from the wall. A dash means the bed never reaches that far. Add a few inches on top for a duvet, which sits proud of the mattress.
At a glance
| What it does | Cabinet dimensions, floor projection and room clearances for a Murphy or wall bed |
|---|---|
| Category | Home & DIY |
| Inputs needed | Mattress size and thickness, ceiling height, clear wall width, room depth |
| Main output | Verdict, cabinet size and projection when open |
| Formula | depth = mattress + 3.75 in; projection = depth + mattress length + 2 in |
| Cost | Free, no sign-up, no download |
How to use the Murphy Bed Size Calculator
- Pick the mattress size and enter its thickness. Thickness sets the cabinet depth, so measure the mattress you actually own.
- Measure the clear wall width between obstructions, the ceiling height, and the room depth wall to wall.
- Enter the skirting board height. Unless it is cut away behind the cabinet, it pushes the whole cabinet off the wall.
- Choose a walkway at the foot: 24 in is the bare minimum, 30 in is comfortable, 36 in takes a wheelchair.
- Read the verdict, then drag the opening slider to watch the swing envelope against anything already in the room.
- If it does not fit, try the other orientation before changing mattress size. It is usually the answer.
Frequently asked questions
How much space does a Murphy bed need when open?
A vertical queen reaches about 96 in from the wall, which is the cabinet depth plus the mattress length plus a foot rail. Add a walkway of at least 24 in at the foot, so the room needs roughly 120 in of depth. Turning the bed horizontal cuts the projection to about 76 in.
How deep is a Murphy bed cabinet?
Mattress thickness plus about 3.75 in, covering the back panel, the deck, an air gap and the face panel. A 10 in mattress needs a 14 in cabinet, a 12 in mattress needs 16 in. Most cabinets sold are 16 to 18 in deep, and the depth is what limits the mattress you can use, not the other way round.
What ceiling height do I need for a Murphy bed?
A vertical cabinet is the mattress length plus about 8.25 in, so a queen wants roughly 89 in including a scribe. Under an 8 ft ceiling that works. Under 7 ft it does not, and the horizontal version, at about 69 in tall, is the way out.
Vertical or horizontal Murphy bed, which is better?
Vertical needs a tall ceiling and a narrow wall, horizontal needs a wide wall and a low ceiling. Horizontal also projects far less into the room, which matters in a small study or a loft. The trade is wall width: a horizontal queen wants about 87 in of wall against 64 in for the vertical.
How thick a mattress can a Murphy bed take?
Work back from the cabinet depth: usable thickness is the depth minus about 3.75 in. Going thicker stops the bed closing, and stuffing it in strains the mechanism. Thickness also changes the balance, so a heavier replacement mattress needs the pistons re-rating.
Do Murphy beds have to be attached to the wall?
Yes, or to the floor. Once the bed is part way down, the whole load is cantilevered off the cabinet with nothing under the foot, and that is the moment it tips. Fix through the top rail into studs, or use floor brackets on masonry.
Why is a Murphy bed lower than a normal bed?
The sleeping surface is the pivot height plus the deck plus the mattress, which for a 10 in mattress comes to about 17 in against 24 in for a divan. If someone struggles to stand up from low seating, a thicker mattress is the simplest fix, so long as the cabinet depth allows it.
Will a Murphy bed hit my ceiling light?
It can, and it happens on the way down rather than at rest. The top corner sweeps an arc, so the clearance you need at any point is the height of that arc, not the height of the open bed. Directly above a vertical queen at 4 ft from the wall you need about 81 in of clearance.
Results are estimates for general information. Allowances follow common wall bed construction, but hardware kits vary, so check the mechanism maker's own dimensions before cutting. A wall bed is a heavy moving assembly: if you are unsure about the wall fixing, have it installed.
Related calculators
- Bed Size Calculator — coming soon
- Room Size Calculator — coming soon
- Plywood Sheet Calculator — coming soon
- Stair Runner Calculator — coming soon