Deck Sizes: Common Dimensions and How Big a Deck You Need
How much deck you need for dining, lounging, a grill or a hot tub, the common sizes in feet and meters, and the board, joist and code dimensions that shape the build.
Common deck sizes are 10 × 10 ft (3.05 × 3.05 m, 100 sq ft), 12 × 12 ft (3.66 × 3.66 m, 144 sq ft) and 12 × 16 ft (3.66 × 4.88 m, 192 sq ft). A table for four with chairs needs about 10 × 10 ft; a table for six needs about 9 × 12 ft before you add a walkway.
- Small deck
- 8 × 10 ft (80 sq ft)
- Dining for 4
- 10 × 10 ft
- Dining + lounge
- 12 × 20 ft or more
- Guard required
- Over 30 in high
On this page
Common deck sizes chart
Decks are usually planned in 2 ft steps because deck boards and joists come in even-foot lengths: 8, 10, 12, 16 and 20 ft. Sticking to those dimensions cuts waste.
| Deck size (ft) | Size (m) | Area | What fits comfortably |
|---|---|---|---|
| 8 × 10 | 2.44 × 3.05 | 80 sq ft (7.4 m²) | Bistro table for two, or two lounge chairs |
| 10 × 10 | 3.05 × 3.05 | 100 sq ft (9.3 m²) | Round table for four, no walkway |
| 10 × 12 | 3.05 × 3.66 | 120 sq ft (11.1 m²) | Table for four or a small sofa set |
| 12 × 12 | 3.66 × 3.66 | 144 sq ft (13.4 m²) | Table for four to six with a walkway |
| 12 × 16 | 3.66 × 4.88 | 192 sq ft (17.8 m²) | Dining for six plus a grill |
| 14 × 20 | 4.27 × 6.10 | 280 sq ft (26.0 m²) | Dining and a conversation set |
| 16 × 20 | 4.88 × 6.10 | 320 sq ft (29.7 m²) | Dining, lounge and grill zones |
| 20 × 20 | 6.10 × 6.10 | 400 sq ft (37.2 m²) | Several zones or a hot tub plus dining |
The first number is usually the depth, measured out from the house, and the second the width along it. Depth matters more than area: a long, shallow deck has plenty of square feet but can be too narrow for a table with chairs pulled out.
How big a deck you need for furniture
Size a deck from the furniture outward. Each zone below includes the furniture plus the clearance to use it: 36 in (91 cm) behind dining chairs so people can pull out and sit, and about 30 in around lounge seating.
| Zone | Furniture | Space needed (ft) | Space needed (m) |
|---|---|---|---|
| Bistro for two | 24 to 30 in table, two chairs | 6 × 6 | 1.8 × 1.8 |
| Dining for four | 48 in round table (a 36 × 60 in table needs 9 × 11 ft) | 10 × 10 | 3.0 × 3.0 |
| Dining for six | 36 × 72 in table | 9 × 12 | 2.7 × 3.7 |
| Dining for eight | 40 × 96 in table | 9.5 × 14 | 2.9 × 4.3 |
| Conversation set | Loveseat, two chairs, coffee table | 10 × 10 to 10 × 12 | 3.0 × 3.0 to 3.0 × 3.7 |
| Two loungers | Two chaises, side table | 8 × 8 | 2.4 × 2.4 |
| Grill station | Grill plus prep side table | 5 × 6 | 1.5 × 1.8 |
| Hot tub | 7 × 7 to 8 × 8 ft tub | 10 × 10 to 11 × 11 | 3.0 × 3.0 to 3.4 × 3.4 |
The dining figures come from simple addition: a 36 × 72 in table plus 36 in on every side is (72 + 72) × (36 + 72) = 144 × 108 in, or 12 × 9 ft. Add a 36 in walkway from the house door to the stairs that does not cut through any zone, and add the zones together. A dining table for six, a grill station and a walkway is why 12 × 16 ft is such a common choice.
Furniture footprints vary; our patio furniture dimensions guide lists typical sizes, and outdoor rug sizes helps define a lounge zone.
Decks built to the IRC are designed for a 40 psf live load plus 10 psf dead load. A filled hot tub with people in it typically puts 80 to 120 psf on its footprint, so it needs its own framing, footings or a slab designed for the load. See hot tub sizes for weights.
The smallest practical deck
The legal minimum is a landing. The IRC (R311.3) requires a landing outside each exterior door at least as wide as the door and at least 36 in (91 cm) deep. For a 36 in door, that is a 3 × 3 ft platform: room to step out and close a screen door, nothing more.
For sitting, about 6 × 8 ft (1.8 × 2.4 m) holds two chairs and a side table, and 8 × 10 ft (2.4 × 3.0 m) holds a bistro set with space to pass. Below about 8 ft of depth, a table with chairs pulled out runs into the rail or the house wall.
Deck height, permits and guards
The height of the deck surface above the ground drives most of the code rules. Requirements below are from the 2021 IRC; many cities amend them, so confirm with your building department before you build.
- Permit exemption: the IRC (R105.2) exempts a deck only if it is no more than 200 sq ft, no more than 30 in above grade at any point, not attached to the house and not serving the required exit door. Most attached decks need a permit.
- Guards: required where the deck surface is more than 30 in (762 mm) above the grade within 36 in horizontally. Guards must be at least 36 in (914 mm) tall, and openings must not let a 4 in (102 mm) sphere pass.
- Stairs: at least 36 in wide, risers no more than 7 3/4 in, treads at least 10 in deep.
- Loads: 40 psf live load plus 10 psf dead load for ordinary decks; heavy snow regions use higher values.
A ground-level deck under 30 in high needs no guard, which is one reason low platform decks are popular: open edges make a small deck feel bigger.
Deck board sizes
Deck boards are sold by nominal size like other lumber, so a 2x6 is not 2 × 6 in. Lengths are 8 to 20 ft in 2 ft steps for wood; composite boards are commonly 12, 16 and 20 ft.
| Board | Actual size (in) | Actual size (mm) | Max joist spacing, boards perpendicular |
|---|---|---|---|
| 5/4 × 6 wood | 1 × 5 1/2 | 25 × 140 | 16 in |
| 2 × 6 wood | 1 1/2 × 5 1/2 | 38 × 140 | 24 in |
| 2 × 4 wood | 1 1/2 × 3 1/2 | 38 × 89 | 24 in |
| Composite or PVC | About 15/16 to 1 × 5 1/2 | About 24 to 25 × 140 | Per manufacturer, usually 16 in or less |
Joist spacing for wood decking comes from IRC Table R507.7. Boards laid on a diagonal need closer joists: 12 in for 5/4 boards and 16 in for 2x boards. Composite and PVC boards must follow their own evaluation report, and many require 12 in spacing on diagonals or on stairs.
How many deck boards you need
A 5 1/2 in board plus a 3/16 in gap covers 5 11/16 in, or about 2.1 boards per foot of deck. A deck 12 ft deep with boards running parallel to the house needs 144 ÷ 5.6875 = 25.3, so 26 rows. If the deck is 16 ft wide, each row is one 16 ft board, so 26 boards in all; buy about 10% extra for defects and cuts.
For other lumber dimensions, see nominal vs actual lumber sizes.
Deck joist spans
Joist size and spacing set how far a joist can run between the ledger or beam and the next beam. These are the prescriptive spans for single-span joists without cantilever, from IRC Table R507.6, for No. 2 grade lumber at 40 psf live load and 10 psf dead load.
| Joist | Southern pine, 12 in o.c. | Southern pine, 16 in o.c. | Southern pine, 24 in o.c. | Douglas fir-larch, hem-fir, SPF, 16 in o.c. |
|---|---|---|---|---|
| 2 × 6 | 9 ft 11 in | 9 ft 0 in | 7 ft 7 in | 8 ft 8 in |
| 2 × 8 | 13 ft 1 in | 11 ft 10 in | 9 ft 8 in | 11 ft 1 in |
| 2 × 10 | 16 ft 2 in | 14 ft 0 in | 11 ft 5 in | 13 ft 7 in |
| 2 × 12 | 18 ft 0 in | 16 ft 6 in | 13 ft 6 in | 15 ft 9 in |
A 12 ft deep deck attached to a ledger can therefore use 2 × 10 joists at 16 in on center with a beam near the outer edge, while 2 × 8 joists would need a beam at about 11 ft. Spans change with snow load and code edition, so use the table your jurisdiction has adopted.
Putting a gazebo or pergola on a deck
- Find the leg footprint. The advertised size of a gazebo is usually the roof. Check the spec sheet for the distance between post centers, which is often several inches smaller.
- Add 2 ft per side. A 10 × 12 ft gazebo needs a deck of at least 14 × 16 ft, and a 12 × 12 ft gazebo about 16 × 16 ft. This leaves a walkway and keeps the eaves inside the deck edge.
- Land posts on framing. Anchor each post through the decking into doubled joists or added blocking, never into deck boards alone. Wind uplift on a hard roof is considerable.
Size guides for both structures: gazebo sizes and pergola sizes.
Frequently asked questions
What size deck do I need for a 10 x 12 gazebo?
Plan for at least 14 × 16 ft (4.27 × 4.88 m). That gives 2 ft on every side of the gazebo for walking around the posts, fixing the anchors into the framing and letting the roof overhang. See our gazebo sizes guide for leg footprints, which are often smaller than the roof size.
If my deck is 10 x 10, should my gazebo be 10 x 10?
Only if the gazebo's leg footprint is smaller than the deck and the posts land on solid framing. Many 10 × 10 gazebos measure 10 × 10 ft at the roof with legs set in by several inches, but you still have no walkway around them. A 8 × 8 ft gazebo, or a deck enlarged to 12 × 12 ft, is the more practical pairing.
How much patio furniture fits on a 120 sq ft deck?
A 10 × 12 ft deck (120 sq ft) holds a dining table for four with chairs, or a loveseat, two armchairs and a coffee table, but not both. Add 3 ft of walkway past a door and the dining set is the practical limit.
Is a 10 by 30 deck big enough?
It has 300 sq ft, enough for two or three zones in a row (for example dining, grill and lounge), but its 10 ft depth is the limit. A table for six needs about 9 ft of depth with chairs pulled out, leaving no room to walk behind the diners. For dining with a walkway, aim for 12 to 14 ft deep.
Should I use 2x6 or 5/4 x 6 deck boards?
2x6 boards (1 1/2 × 5 1/2 in) are stiffer and can span joists 24 in on center; 5/4 × 6 boards (1 × 5 1/2 in) need joists at 16 in on center and look less chunky. Ordinary 1x6 boards (3/4 in thick) are not rated for decking. Composite boards are about 1 in thick and usually need 16 in spacing or less.
What is the minimum size for a deck or landing in cm?
The IRC requires a landing at an exterior door at least as wide as the door and at least 36 in (91 cm) deep in the direction of travel. As a usable seating deck, about 8 × 8 ft (2.4 × 2.4 m) holds a small table and two chairs.