Deck Cost Calculator
Estimate what it costs to build a deck — enter the size, material, height and railing to get a low-to-high installed total, the cost per square foot, and a materials-versus-labor breakdown.
United States — national average · 2026 prices
Material only unless stated as installed. Excludes tax, permits and local labour. Verify with local suppliers — see how we calculate.
How this calculator works
Every figure above comes from the formula below, applied to the assumptions listed. Nothing is looked up from a hidden table — you can reproduce the result by hand.
Formula
deck area = length × width
decking cost = area × material rate per sq ft × height multiplier
railing = lineal feet of open side × $25–$60 per ft
total = decking + railing, split about 45% materials / 55% labour
Assumptions & limits
- Installed rates per sq ft: pressure-treated $15–$25, cedar or redwood $20–$35, composite $30–$60, PVC $35–$70, tropical hardwood $30–$60 (2026 US national ranges).
- Height multiplier is 1.0 ground level, 1.15 raised, 1.30 elevated, covering taller footings, beams, bracing and guard railing.
- Railing length is derived from the number of open sides: two sides = length + width, three = length + 2 × width, four = full perimeter.
- Labour is taken as roughly 55% of the installed figure — so the DIY materials-only line is about 45%.
- Excluded: stairs, built-in benches, lighting, pergolas, multi-level framing, permit fees and any ledger or footing work driven by local code.
Worked example
A 16 × 12 ft ground-level pressure-treated deck with railing on three open sides
- Area = 16 × 12 = 192 sq ft
- Decking = 192 × $15 to $25 × 1.0 = $2,880 to $4,800
- Railing = 16 + 2 × 12 = 40 lineal ft × $25 to $60 = $1,000 to $2,400
- Total = $3,880 to $7,200
Result:About $3,880 to $7,200 installed, near $29 per sq ft at the midpoint — roughly $2,500 in materials if you build it yourself.
Built and maintained by Christoph Ballmer, Honeygoat GmbH
Method and constants last checked against the calculator code on August 17, 2026. Independent trade review is not yet in place for this calculator — see how we handle review.
Read the site-wide calculation methodology · estimate vs. quote and safety limits
How much does it cost to build a deck?
In 2026 a built deck typically runs $25 to $60 per square foot installed, so a common 300–400 sq ft deck lands between roughly $7,500 and $24,000. The figure swings on four things: the deck's size, the decking material, how high it sits off the ground, and how much railing and stairs it needs. Pressure-treated wood is the cheapest build; capped composite and PVC cost more up front but need far less upkeep. The calculator above prices your exact size and choices and splits the total into materials and labor, so you can see what a DIY build would save.
Deck cost formula
A full deck quote is more than one price per square foot. Estimators build it up from four layers — the framing (substructure), the decking surface, the railing, and any stairs — then add permits and tear-off:
total = (substructure $/sq ft + decking $/sq ft) × area × height factor + railing length × rail rate + stairs + permit + tear-off
- Substructure (footings, posts, beams, joists, ledger): about $8–$18 per sq ft, more for tall or hillside decks that need deep footings.
- Decking surface: the board material itself, roughly $3–$20 per sq ft in material depending on species/brand (see table).
- Railing: about $10–$50 per linear foot installed (~$30 average), with cable and glass at the top of that range.
- Stairs: roughly $150–$350 per step, or about $1,000–$2,000 per flight.
- Permit: commonly $50–$500; large or engineered decks can run higher.
Worked example: a 16 × 20 ft composite deck
Say you want a 16 ft × 20 ft = 320 sq ft composite deck, about 3 ft off the ground, with railing on the two open sides (36 ft) and one short flight of stairs:
- Substructure: 320 sq ft × $12/sq ft = $3,840
- Composite decking installed: 320 sq ft × $30/sq ft (board + labor) = $9,600
- Railing: 36 lin ft × $30/lin ft = $1,080
- Stairs (one flight, ~5 steps): $1,400
- Permit: $250
Adding those gives roughly $16,170, or about $51 per square foot all-in — squarely in the mid-to-upper range for composite. Swap in pressure-treated boards and the same deck drops to around $9,000–$11,000. The calculator runs this math for your size and material instantly.
Deck cost by material
| Material | Installed $/sq ft | Notes |
|---|---|---|
| Pressure-treated wood | $15 – $25 | Lowest cost, needs sealing every 2–3 yrs |
| Cedar / redwood | $20 – $35 | Natural look, rot-resistant |
| Composite (Trex) | $30 – $60 | Low maintenance, ~25-yr warranty |
| PVC (AZEK) | $35 – $70 | Most weather- and stain-resistant |
| Tropical hardwood (Ipe) | $50 – $65 | Premium, very dense and durable |
Cost figures are 2026 estimates and vary widely by region, deck height and access.
Cost by deck size (composite, installed)
| Deck size | Area | Typical range |
|---|---|---|
| 10 × 10 ft | 100 sq ft | $3,000 – $6,000 |
| 12 × 16 ft | 192 sq ft | $5,800 – $11,500 |
| 16 × 20 ft | 320 sq ft | $9,600 – $19,200 |
| 20 × 20 ft | 400 sq ft | $12,000 – $24,000 |
The add-ons that drive the bill up
The base price-per-square-foot covers a simple, low rectangle. These line items are what separate a $9,000 deck from a $24,000 one:
| Item | Typical cost | When it applies |
|---|---|---|
| Railing | $10 – $50 / lin ft | Required on most raised decks; cable/glass at the high end |
| Stairs | $150 – $350 / step | Each flight down to grade |
| Deeper / taller footings | +$8 – $18 / sq ft | Elevated or hillside decks, deep frost lines |
| Tear-off of old deck | $500 – $1,000 | Replacing an existing deck |
| Permit & inspection | $50 – $500 | Almost always required for attached/raised decks |
How much of a deck is labor?
Labor is the single biggest share of a built deck — usually 50% to 70% of the total, or roughly $11–$22 per square foot for a standard pressure-treated build, and more for elevated or complex designs. That is why doing the build yourself can cut the cost roughly in half. The estimate above splits the midpoint about 45% materials and 55% labor; a DIY build keeps the labor portion in your pocket but adds your time and tool costs.
Waste and ordering extra
Add about 10% extra decking for cuts, the occasional bad board and future repairs — bump that to 15% for a diagonal, picture-frame or herringbone board layout, which produces more offcuts. Buying boards from the same production batch up front also avoids slight shade differences later. To size the boards, joists and fasteners precisely, run the deck board calculator; for a ground-level build on blocks, use the floating deck calculator.
Common deck-cost mistakes
- Pricing only the decking. The boards are often a third of the job — framing, railing and stairs make up the rest.
- Forgetting the permit. Skipping it can mean fines, a forced rebuild, or a failed home sale; budget $50–$500.
- Ignoring height. A 2-foot deck and a 10-foot deck on the same footprint are very different prices — taller decks need longer posts, bigger footings and guard railing.
- Underbuying boards. Running short mid-project risks a batch/color mismatch on the refill; the 10% waste allowance covers this.
- Comparing quotes by total only. Always compare per-square-foot and confirm what's included (footings, railing, stairs, disposal).
When to DIY vs hire a pro
A low, freestanding, ground-level deck under about 200 sq ft is a realistic DIY weekend-plus project and is where the labor savings are biggest. Hire a licensed deck builder once the deck is attached to the house (the ledger connection is a leading cause of deck collapses), sits more than ~30 inches off the ground, spans long beams, or sits on a slope — these need engineered footings, proper flashing and an inspection. A deck that passes inspection is also the one that survives a home sale: an unpermitted or non-compliant structure turns up in the buyer's inspection report and gets negotiated against the price, which is where the saving on a cheap build goes.
Pouring footings? Size the concrete with the concrete calculator, and if your deck carries a roof, check the slope with the roof pitch calculator. Hiring out? Compare quotes from local deck builders below.
These are planning estimates only — material and labor prices change by season and region. Verify with a local deck builder or supplier and your building department before you buy or build.
Frequently asked questions
Do I need a permit to build a deck?
In most US jurisdictions, yes — any deck attached to the house, or a freestanding deck above a certain height or size (often around 30 inches high or 200 square feet), needs a building permit and at least one inspection. Permit fees commonly run $50 to $500, and larger or engineered decks cost more. Building without a required permit can mean fines, a forced rebuild, or trouble when you sell the home, so check with your local building department before you start.
How much does a 20x20 deck cost?
A 20x20 deck is 400 square feet. In pressure-treated wood that is roughly $10,000 to $14,000 installed; in composite it is more like $16,000 to $24,000, and premium PVC or hardwood pushes it higher. Railing on the open sides, stairs and elevated footings add to those figures. Enter 20 by 20 and your material above for a tailored low-to-high estimate.
Does a new deck add value to your home?
Yes — a well-built deck is one of the better outdoor returns, recouping roughly 50% of its cost in added home value on average, with wood decks often returning a bit more of their lower cost than premium composite. The bigger payoff is usability, but a code-compliant, permitted deck also protects resale, while an un-permitted or unsafe one can scare off buyers and inspectors.
How can I build a deck for less money?
The biggest savings come from choosing pressure-treated wood over composite, keeping the deck low and ground-level to avoid tall footings and guard railing, sticking to a simple rectangle, and doing the labor yourself where it is safe to (labor is 50 to 70% of the cost). A freestanding ground-level or floating deck also skips the more involved ledger connection to the house. Buy boards in one batch to avoid waste, and get at least three itemized quotes if you hire out.
How much does it cost to build a deck?
Installed, a deck typically runs about $15–$25 per square foot for pressure-treated wood, $20–$35 for cedar, $30–$60 for composite like Trex, and $35–$70 for PVC. A average 300 sq ft deck therefore lands roughly between $6,000 and $18,000 depending on material, height and railing. Enter your size and material above for an estimate.
How much does a 12×12 deck cost?
A 12×12 deck is 144 square feet. In pressure-treated wood that is about $2,200–$3,600 installed; in composite it is more like $4,300–$8,600. Adding railing, stairs or height raises it. The calculator prices your exact size and choices.
Is a composite or wood deck cheaper?
Pressure-treated wood is cheaper to build — often half the up-front cost of composite. Composite (Trex, TimberTech) and PVC (Azek) cost more initially but need far less maintenance and last longer, so they can be cheaper over the deck’s life. The calculator lets you compare materials side by side.
How much of a deck’s cost is labor?
Labor is usually around half of a built deck’s cost, sometimes more for elevated or complex designs. The estimate above splits the midpoint roughly 45% materials and 55% labor; doing it yourself saves the labor portion but adds your time and tool costs.
Does the cost include railing and stairs?
Railing adds meaningfully to the total — often $20–$60 per lineal foot installed — and stairs add a few hundred dollars per flight. The calculator includes a railing option and a height factor; unusual features like built-in benches, lighting or multiple levels would add more.
What is the 3/4/5 rule for decks?
It is the field method for getting a corner perfectly square. Measure 3 ft along one side from the corner and 4 ft along the other; the diagonal between those two marks is exactly 5 ft only when the corner is a true 90 degrees - the 3-4-5 right triangle from the Pythagorean theorem. On bigger frames use multiples like 6-8-10. Framers use it when laying out the ledger, beams and footings, because a frame that starts out of square stays out of square.
How much would a 16x20 deck cost?
A 16x20 deck is 320 square feet. Installed at ground level, that is roughly $4,800-$8,000 in pressure-treated wood or $9,600-$19,200 in composite. Railing on three open sides adds about 52 lineal feet - another $1,300-$3,100 installed. Elevated versions cost more for footings, framing and code-required guard railing. Set the exact size, material and height above for a tailored range.