Deck Cost Calculator

Getting a deck estimate takes five quick entries. The tool prices the deck surface by size and material, then adds railing around the edge and your contingency.

1. Enter the deck length and width in feet.
2. Pick your decking material. Pressure-treated pine is the lowest cost, cedar sits in the middle, composite costs more up front, and hardwood is the premium choice.
3. Tick the railing box if the deck needs railing, then set your contingency. 10% is typical.
4. Press Calculate, or press Enter. The total appears first and large, with the base cost, the railing cost and the contingency below. Press Reset to clear the form and start over.

The deck cost formula is total = (area x rate per sq ft + railing) x (1 + contingency). The area is the length times the width, and the railing is priced at $35 per linear ft of deck perimeter, which is two times the length plus the width.

The installed rates per square foot are $35 for pressure-treated pine, $38 for cedar, $55 for composite, and $60 for hardwood. These are midpoints of the ranges in the HomeGuide 2026 deck cost guide, which lists $25 to $50 per square foot installed for a new deck. Our deck calculator works out how many boards and joists the same deck needs.

A deck is 16 ft long and 12 ft wide, built with composite decking, with railing and a 10% contingency. Here is exactly what the calculator does.

1. Deck area: 16 x 12 = 192 sq ft.
2. Base cost: 192 x $55 = $10,560.
3. Railing: the perimeter is 2 x (16 + 12) = 56 linear ft, so 56 x $35 = $1,960.
4. Contingency: 10% of $12,520 = $1,252.
5. Total: $12,520 + $1,252 = $13,772.

As a second check, a 12 by 12 ft pressure-treated deck costs 144 x $35 = $5,040, plus 10% contingency, for $5,544 before railing. The same steps work for any deck, so try your own numbers in the tool above.

Material is the biggest lever. Pressure-treated pine is the cheapest decking, cedar costs a little more and weathers to a silver grey if left unstained, composite costs more up front and needs almost no upkeep, and hardwood costs the most and lasts the longest. The rate you pick should match the boards you actually plan to buy.

Height matters too. A ground level deck costs less per square foot than an elevated deck, because an elevated deck needs taller posts, deeper footings, stairs and more railing. Size also matters, since a small deck spreads the fixed costs of footings and permits over fewer square feet. Slope, poor access and rocky soil all push labor up, and local labor rates vary widely by city.

Railing is priced by the running foot, not by the deck area, which is why this calculator uses the deck perimeter. A deck with railing on all four sides costs more than a deck with railing on two sides, so measure only the sides that need it and adjust the length if part of the edge is open. Stairs are a separate cost, and a long stair run with a landing can add a large amount to the job.

Most towns require a permit for an attached or elevated deck, and a deck permit typically costs $230 to $500. The permit covers the footing depth, the framing and the railing height, so a contractor who skips it can leave you with a deck that fails inspection. Check the local rules before you order materials.

Keep the deck low and simple. A ground level deck avoids stairs and tall posts, and a rectangular shape wastes fewer boards than a deck with curves or many angles. Pressure-treated pine keeps the material cost down, and staining it every two or three years protects it from rot.

Get three itemized bids before you set a budget, and check that each one lists the decking, the framing, the railing, the footings and the permit separately. Keep your 10% contingency untouched until the footings go in, because that money is for the surprises you cannot see yet. Our concrete calculator prices the footing concrete, and our lumber calculator prices the framing boards.