Deck cost calculator

How much does a deck cost?

A typical 192-square-foot deck with railing and stairs costs between $5,330 and $11,540 installed, depending almost entirely on decking material. That works out to roughly $32.67 to $52.27 per square foot all-in, covering decking, substructure, railing, stairs, hardware, permit and labor rather than the boards alone.

Those are national averages. Your state's labor market moves them by up to 35% in either direction: the composite deck above costs $7,379 in Mississippi and $8,859 in Hawaii. Elevated and complex-shaped decks push higher still.

Deck size guide: what common sizes cost

Most people come to a deck calculator with a size already in mind. A 12 × 12 deck is 144 square feet and costs about $6,449 in composite. A 14 × 20 is 280 square feet at about $10,765, a 16 × 20 is 320 square feet at about $11,985, and a 20 × 20 is 400 square feet at about $14,425.

In pressure-treated pine the same footprints drop sharply, $9,112 for the 16 × 20 and $10,834 for the 20 × 20. Material is the biggest lever available on any of these sizes, and it is the one decision worth making before you talk to a contractor.

Two things are worth noticing in those numbers. Per square foot, cost falls as the deck grows, $38.45 on the 14 × 20 against $36.06 on the 20 × 20, because the permit, the ledger and the stairs are fixed regardless of area. And the difference between a 14 × 20 and a 16 × 20 is only about $1,220 for 40 more square feet, which is the cheapest space you will ever add to a house. If you are torn between two sizes, build the larger one.

Deck cost by material: pressure-treated vs cedar vs composite vs PVC

Decking material is the single biggest lever on the total, spanning $4 to $14 per square foot for the boards alone, a four-fold spread before anyone installs them. On the 192-square-foot deck above that is $6,273 in pressure-treated pine, $7,022 in cedar, $7,997 in composite and $8,427 in PVC.

Pressure-treated pine is the default because it is cheapest and every lumberyard stocks it, but it needs resealing every one to two years and lasts 10-15 years. Cedar buys real wood warmth and natural rot resistance for about $749 more, and still wants sealing to hold its colour. Run the composite deck calculator setting and the picture changes: $1,724 more upfront than pine, no sealing ever, and 25-30 years of service. PVC costs more again and is the right answer beside a pool or on the coast, where constant moisture is the governing problem.

Upfront price and lifetime cost rank differently, and both belong in the decision. Per year of service the same deck is $502 in pressure-treated pine against $291 in composite, and that comparison does not count the sealer, or the weekend spent applying it every eighteen months. If you are moving inside five years, upfront cost is the number that matters; if this is a long-term house, the annual figure is the honest one.

Trex and composite decking costs

Trex is the brand most people mean when they say composite, and it is sold in tiers rather than at one price. Enhance Basics runs about $5 per square foot for boards alone, Enhance Naturals about $7, Select about $9, and the premium Transcend line about $12. TimberTech, Fiberon, Deckorators and MoistureShield all compete at those same tiers.

Our calculator prices composite at a blended $9 per square foot, which sits between Select and Transcend and reflects where most installed composite decks actually land. If you have a quote for a specific product, adjust the board line and leave everything else alone, brand affects the surface and nothing beneath it.

That is the point worth carrying into a contractor conversation. Framing, railing, stairs, hardware and labor are identical whichever composite board goes down, and together they are well over half the project. The full spread from the cheapest Trex tier to the dearest is about $1,344 on a 192-square-foot deck, worth having an opinion about, but not the decision that sets your budget.

How many deck boards and footings you need

Board count is simple arithmetic once you know the coverage. A 16-foot board 5.5 inches wide covers 7.3 square feet, so a 320-square-foot deck needs 44 boards on paper and about 50 ordered once the 12% cut-and-damage allowance is added. Laying boards diagonally adds roughly 15% more, because every board meets the joists at an angle and every cut leaves a waste piece.

Underneath, a deck attached to the house needs poured footings that bear below the local frost line, six to nine of them on a 16 × 12 deck, and deeper in the north than the south. Precast deck blocks are an alternative only for a freestanding deck: set 4 to 6 feet apart, a 12 × 12 floating deck takes 9 to 16 blocks.

Whatever the deck is sitting on, it is designed to carry 50 lbs per square foot, 40 psf of live load plus 10 psf for the structure itself. Check every corner with the 3-4-5 rule before fastening: 3 feet along one edge, 4 along the other, and exactly 5 on the diagonal.

A free deck calculator with no signup

This is a free deck calculator in the ordinary sense of the word: no email address, no phone number, no account, and no handing your project details to three contractors who will call you for a fortnight. Enter your dimensions, get an itemized estimate, close the tab if that is all you needed.

Every line is shown separately, decking, substructure, railing, stairs, hardware, waste allowance, labor and permit, because a single bottom-line number is not much use when you are deciding whether to drop the railing or downgrade the boards. The formula is documented on this page rather than hidden, and the labor line comes from Bureau of Labor Statistics construction earnings data for your state rather than an invented regional percentage.

No contractor pays to appear here and nothing on this page is a lead form. What the estimate is: a planning range good enough to budget against and to sanity-check a quote. What it is not: a quote. Anyone who prices your specific site will find things a calculator cannot see.

DIY vs professional installation

Labor is 40-50% of an installed deck, so building it yourself is the largest single saving available. The composite deck above drops from $7,997 installed to about $6,185 DIY, roughly $1,812, leaving materials, hardware, the permit and a tool rental allowance.

The honest caveat is that a deck is not a fence. Framing to span tables, flashing the ledger correctly and getting footings below frost depth are code requirements with real consequences, and the ledger connection to the house is the most common inspection failure in residential construction. Deck collapses almost always trace back to that one detail.

A reasonable middle path is hiring out the substructure and doing the surface yourself, or building freestanding and avoiding the ledger entirely. Either way, permit the work and take the inspections. They are the cheapest structural review you will ever get.

When to build: seasonal pricing

Deck season runs March to September, and prices follow demand. Booking a build for late autumn or winter in a mild climate frequently saves 10-15% on labor, because crews are quoting into an empty schedule rather than a six-week backlog. The same crew that is booked solid in May is calling you back in November.

Material pricing moves on a different clock. Framing lumber and treated pine track commodity markets and are usually softest in late autumn and winter; composite and PVC are manufactured goods with far steadier pricing and periodic promotions instead. The material trend chart above tracks the producer price index for lumber so you can see where prices sit against recent history.

Practical constraints on winter builds: concrete for footings should not be placed into frozen ground, so a deep frost line effectively closes the season in northern states. In the South and on the West Coast, a winter build is genuinely cheaper and the deck is ready before you want to use it.

What drives deck cost

Square footage sets the baseline, but cost per square foot falls slightly as decks get larger. Fixed costs like the permit, the ledger and the stairs spread across more area.

Decking material is the single biggest lever, spanning $4 to $14 per square foot for boards alone, a 4x spread.

Height off the ground adds up to 45% because it changes the entire substructure, not just the posts. It also triggers the railing requirement and, past 30 inches, the permit in most jurisdictions.

Railing is priced per linear foot and accounts for 15-20% of the total. Cable railing costs three times what wood does.

Stairs are expensive per step. A full staircase adds roughly $1,850 because stringers, treads and a landing footing are all involved.

Shape is the quiet one. An L-shape adds about 12% to labor and a wraparound about 25%, and a wraparound carries 40% more perimeter, which multiplies straight into the railing line.

Substructure is invisible and unavoidable. Framing, footings and hardware routinely account for 35-45% of an installed deck, and frost depth in your state sets how deep those footings have to go.

How we calculated these estimates

Every figure on this page comes from the same open formula the calculator above uses. We start from a 2026 national baseline for materials and installed labor, apply the state labor multiplier published by the Bureau of Labor Statistics for construction trades, then add the line items your inputs call for: gates, corners, removal, permits and a waste allowance. Nothing is hidden behind a lead form, and no contractor pays us to appear here. The result is a planning range, not a quote. The low figure assumes straightforward access and an efficient crew, and the high figure assumes obstacles, difficult access, or premium material grades.