Deck cost by size, at a glance
The table below is the ProjectCostPro deck calculator’s 2026 installed ranges for the most-built deck sizes. Each figure is a turnkey band for an attached, elevated deck including substructure, railing, stairs, permit, and labor — not just boards. Pressure-treated is the baseline; composite (Trex, TimberTech) and PVC (AZEK) add a modest premium because the frame, railing, stairs, and labor underneath are identical.
Why small decks cost more per square foot
Cost per square foot is the number everyone wants, and the one most likely to mislead. It falls as a deck gets bigger, because several of the largest line items barely change with size — a stair run, a code-height railing, the building permit, and crew mobilization cost about the same on a 100 sq ft deck as on a 300 sq ft one. A small deck simply has fewer square feet to spread them over.
So a “$50 per square foot” rule of thumb is only right in the middle of the range. Below about 150 sq ft, expect to pay more per foot; above 400 sq ft, less. The single biggest per-foot saving is skipping the parts that don’t scale:
a ground-level 12×16 (about 12 in off the ground) with no railing, no stairs, and no permit runs about $6,400–$10,700 — roughly 30% less than the same footprint built 36 in high with a railing and stairs at $9,000–$15,400.
What each range includes
Unlike a bare “boards per square foot” quote, the ranges above are a complete deck. Every band is built from the same line items the calculator prices individually:
- Substructure — pressure-treated joists, beams, posts, and concrete footings. The frame is PT lumber even under a composite or PVC deck.
- Decking — the boards themselves, from PT at roughly $4.70–$8/sf to premium composite at $8–$13/sf and PVC at $9–$13/sf.
- Railing — a guard is required by the IRC once the walking surface is more than 30 in above grade, measured within 36 in horizontally of the open edge (local amendments control); runs from wood at $35–$60 per linear foot up through aluminum, cable, and glass.
- Stairs — typically $210–$350 per step; a 5-step run off an elevated deck adds roughly $1,030–$1,750.
- Permit — a flat jurisdictional fee, usually $50–$300, not marked up.
- Labor — framing and board installation, benchmarked to BLS carpenter wage data plus contractor markup.
Drop the railing, stairs, or permit — as on a ground-level deck — and the total falls accordingly. Add wraparound railing, multiple stair runs, a built-in bench, or a diagonal board layout and it climbs. The calculator lets you change the size, height, decking, railing, stairs and permit; benches, extra stair runs, wraparound railing and diagonal layouts are custom work it does not price, so have them quoted separately.
Deck cost by material (same 12×16)
Holding size constant at a 12×16 (192 sq ft) shows how little the board choice moves the total, because everything under the boards is the same:
The upgrade from wood to composite is only about 8–10% of the total — far less than most homeowners expect — and it eliminates the stain-and-seal a PT deck needs every 1–3 years. For the full 10-year maintenance math, see composite vs pressure-treated deck cost.
The three most-built sizes
- 12×16 (192 sq ft) — $9,000–$15,400 in PT. The default American family deck: room for a table and a grill, and small enough to keep the budget in check. The best-value size for most yards.
- 16×20 (320 sq ft) — $13,200–$22,600 in PT. A true entertaining deck — separate dining and lounge zones — and one of the cheapest sizes per square foot at $41–$71/sf.
- 20×20 (400 sq ft) — $15,700–$26,900 in PT. A large deck for full outdoor living; at this size an entry-composite upgrade adds about +$500–$1,100, and the maintenance it saves starts to matter.
Price your exact deck size →
Frequently asked questions
How much does a deck cost by size?
Installed 2026 planning ranges run about $5,800–$9,900 for a 10×10 (100 sq ft) pressure-treated deck, $9,000–$15,400 for a popular 12×16 (192 sq ft), $13,200–$22,600 for a 16×20 (320 sq ft), and $18,300–$31,400 for a 20×24 (480 sq ft). Each range includes substructure, railing, stairs, permit, and labor for an attached, elevated deck; composite and PVC add roughly 8–18% over pressure-treated.
How much does a 12x16 deck cost?
A 12×16 (192 sq ft) pressure-treated deck typically runs $9,000–$15,400 installed in 2026, including substructure, railing, stairs, permit, and labor, at 36 in high and attached to the house. The same deck in entry composite (Trex Enhance, TimberTech Edge) runs about $9,200–$16,000, and in PVC about $10,300–$17,000.
How much does a 16x20 deck cost?
A 16×20 (320 sq ft) deck runs about $13,200–$22,600 installed in pressure-treated, $13,500–$23,500 in entry composite, and $15,300–$25,300 in PVC — roughly $41–$71 per square foot in PT, lower than a small deck because the stairs, railing ends and permit are spread over more area.
How much does a deck cost per square foot?
It depends heavily on size, which is why a single per-foot figure misleads. In pressure-treated, a small 10×10 deck costs $58–$99 per square foot because stairs, railing and the permit are near-fixed, while a large 20×24 falls to $38–$65 per square foot. Bigger, simpler decks are cheaper per foot; smaller or more detailed ones cost more.
Why do small decks cost more per square foot?
Because several big line items barely change with size. A stair run, a code-height railing, the building permit, and crew mobilization cost almost the same on a 100 sq ft deck as on a 300 sq ft deck, so a small deck has fewer square feet to spread them across. That is why per-square-foot cost falls as decks get larger, and why a ground-level deck with no railing or stairs is dramatically cheaper per foot.
Does deck size or material drive cost more?
Size drives the total more than material does. Going from a 12×16 to a 20×24 roughly doubles the installed price, while switching that 12×16 from pressure-treated to composite adds only about 8–10% — because the framing, railing, stairs, permit, and labor are the same regardless of the board on top. Pick the size for how you will use the deck first, then choose the material.
