How Big Is a 30×40 Room?
A 30×40 foot room is 1200 square feet (111.5 m²) — roughly 28.4 king-size beds of floor space — approaching the footprint of a two-car garage.
30×40 ft at a Glance
A flat rectangle only tells you so much. Run the full calculator or draw this room in 3D below.
Is a 30×40 Room Big?
It depends entirely on what the room is for. At 1200 sq ft, here's how a 30×40 ft space rates against typical room sizes:
| As a... | Verdict | Typical Range |
|---|---|---|
| Living Room | above typical | Above the typical range (up to 400 sq ft) |
| Bedroom | above typical | Above the typical range (up to 250 sq ft) |
| Dining Room | above typical | Above the typical range (up to 300 sq ft) |
| Home Office | above typical | Above the typical range (up to 200 sq ft) |
| Kitchen | above typical | Above the typical range (up to 300 sq ft) |
| Bathroom | above typical | Above the typical range (up to 150 sq ft) |
Benchmarks from our standard room dimensions guide.
Planning a 30×40 Room
30×40 is the most common size of American pole barns and steel shop buildings, sized around three 10-ft bays and a 40-ft length that takes a Class A motorhome. At 1,200 sq ft it is also the footprint of a three-bedroom ranch house, and 'how big is a 30×40 shop' is one of the most searched questions about any dimension.
A 1:1.33 rectangle, 360 in wide and 480 in long. The width divides into three 120-in bays, each wide enough for a full-size vehicle with 44 in of door clearance (76 + 44 = 120), and the length takes a 40-ft motorhome (480 in) with no room to spare or a 35-ft one with 60 in. Doors go on the 30-ft end wall (three 9-ft doors: 3 × 108 + 2 × 12 + 2 × 6 = 348 in) or on the 40-ft side.
What this size is best used for
- 1Three-bay shop with RV storage
A 35-ft motorhome (420×102 in) in the right bay along the 40-ft length with 60 in in front, two pickups nose-in in the left and centre bays (232 in each, 248 in of depth behind them), and a 240-in workshop strip behind the pickups' bays.
- 2Workshop with a lift
A two-post lift needs a 144×144-in footprint plus 36 in each side: 216 in of the 360-in width, leaving 144 in for a 30-in bench wall and a 114-in aisle; the 480-in length gives 336 in behind the lift for a saw, a welding table and a compressor.
- 3Three-bedroom house footprint
Three 12×12 bedrooms along one 40-ft wall (432 in of 480, 48 in for a hall end), a 12×14 living room, a 10×12 kitchen and a 5×8 bath along the other side, and a 48-in hall between them: 144 + 48 + 168 = 360 in of width.
Three-bay shop with RV storage in a 30×40 building
Furniture sizes are the same true-to-scale pieces in the RoomSketch3D catalog; clearances are what is left after each step.
- End wall (30 ft): three overhead doors, two 9-ft doors (108 in each) for the vehicle bays and a 10-ft door (120 in) for the RV bay on the right, with 6-in piers and 6-in jambs: 6 + 108 + 6 + 108 + 6 + 120 + 6 = 360 in exactly. A 12-ft RV door would push the total to 396 in and needs the wider 30×44 building.
- Right bay (120 in wide, full 480-in length): a 35-ft motorhome (420 in) parks with 60 in at its nose; its 102-in width leaves 9 in each side, so the bay walls stay bare and the RV backs in with a spotter.
- Left and centre bays: pickups (80×232 in) nose-in, 20 in from each bay's sides and 40 in between them (20 + 80 + 40 + 80 + 20 = 240 in of the two bays' 240 in). Behind their tailgates, 480 − 232 = 248 in of depth, of which the rear 240 in are the workshop.
- Workshop strip (240 × 240 in): a 144-in bench 30 in deep across the back wall, a table saw on the strip's centreline with its blade 120 in from the back wall (120 in of outfeed, 96 in of infeed to the pickups' tailgates), 24-in shelving along the left wall, and a 60-in welding table plus a 30×30-in compressor in the rear left corner. Side entry door on the left 40-ft wall within the workshop strip.
Mistakes this size invites
- A 40-ft motorhome: 480 in is the interior length only if the doors are on the end wall and the RV touches both walls, so 30×40 stores a 40-footer with the door closed by inches or not at all — builders quote 30×44 for it.
- Doors on the 40-ft side wall to save the end wall: each vehicle then needs to turn 90° inside a 360-in width, and a 232-in pickup cannot.
What Furniture Fits in a 30×40 Room?
Working from 1200 square feet with standard walkway clearances (36 inches), here's what comfortably fits depending on how you use the room:
Maximum Furniture Sizes for a 30×40 ft Room
Lists like this can't tell you if it actually works
"A 3-seater sofa fits" is true — until the door swing eats two feet of wall, the radiator blocks the long wall, or the walkway to the window shrinks to 20 inches. The only way to know your layout works is to see it: draw the 30×40 ft room, place real furniture at true scale, and check the flow.
That's exactly what RoomSketch3D does. Drag-and-drop true-to-scale furniture pieces into your exact room and walk through it in 3D — before you buy, move, or assemble anything.
Draw your 30×40 ft room and see what fits
Stop imagining layouts. Build this exact room in RoomSketch3D, try furniture arrangements in minutes, and see it in 2D & 3D.
One-time $19.99 purchase. No subscription. True-size furniture, custom sizes.
Frequently Asked Questions
How many square feet is a 30x40 room?
A 30x40 room is 1200 square feet (30 ft × 40 ft = 1200 sq ft), which is 111.5 square meters. Its wall perimeter is 140 feet, the figure you need for baseboard, wallpaper and cable runs.
What is a 30x40 room in meters?
A 30x40 foot room measures 9.14 × 12.19 meters, for a total area of 111.5 square meters.
What is a 30x40 room best used for?
Three-bay shop with RV storage. A 35-ft motorhome (420×102 in) in the right bay along the 40-ft length with 60 in in front, two pickups nose-in in the left and centre bays (232 in each, 248 in of depth behind them), and a 240-in workshop strip behind the pickups' bays.
What is the most common layout mistake in a 30x40 room?
A 40-ft motorhome: 480 in is the interior length only if the doors are on the end wall and the RV touches both walls, so 30×40 stores a 40-footer with the door closed by inches or not at all — builders quote 30×44 for it.