Deck Cost Calculator
Estimate the total cost to build a deck from its size, your price per square foot, and a waste allowance for cuts and offcuts.
Reviewed by the CalcCafe editorial team · Last updated 1 July 2026 · How we test our tools
Example
A 16 ft × 12 ft deck is 192 sq ft. At $35 per square foot with a 10% waste allowance, the cost is 192 × $35 × 1.10 = $7,392, an effective $38.50 per square foot once waste is included.
How it works
Area = length × width. Total cost = area × price per square foot × (1 + waste% ÷ 100). The effective cost per square foot is the total divided by the deck area, so it reflects the price plus your waste allowance.
Good to know
Decking projects are usually quoted per square foot, so the fastest way to sanity-check a bid or plan a budget is to multiply your deck's footprint by a realistic square-foot price and pad it for waste. This tool does exactly that: enter the length and width, a blended price per square foot that reflects your material and labor, and a waste percentage, and it returns the total along with the deck area and the effective per-square-foot cost.
The price-per-square-foot field is where most of the uncertainty lives. Pressure-treated pine decks sit at the low end, cedar and composite boards land in the middle, and premium hardwoods or elaborate multi-level designs push far higher. Whether that number is materials-only or includes labor is up to you — just keep it consistent. If a contractor quotes materials and labor separately, add them together before entering the figure.
The waste allowance covers the offcuts, miter cuts, and the occasional warped board you set aside. Ten percent is a reasonable default for a simple rectangular deck; bump it toward 15% or more for diagonal decking patterns, picture-frame borders, or angled and multi-level layouts that generate more scrap. Because the allowance is applied on top of the base cost, the effective per-square-foot figure the tool reports is always a little above the price you entered.
Treat the result as a planning estimate, not a firm quote. It does not separately model footings, railings, stairs, permits, demolition of an old deck, or regional labor rates, all of which can move the real number substantially. For a build you intend to commission, collect itemized quotes and confirm any permit requirements with your local building department.
Frequently asked questions
How much does it cost to build a deck per square foot?
It varies widely by material and whether labor is included. Pressure-treated wood decks are often cheapest, while composite and hardwood decks cost more, and adding railings, stairs, or multiple levels raises the per-square-foot figure. Enter a price that matches your material and labor mix.
Should I add a waste allowance for decking?
Yes. A 10% allowance is common for a simple rectangular deck to cover offcuts and miter cuts; increase it for diagonal patterns, picture-frame borders, or angled layouts that produce more scrap.
Is my data uploaded anywhere?
No — this calculator runs entirely in your browser. Your inputs never leave your device, and it works offline once loaded.
Is this calculator free?
Yes, completely free with no sign-up and no limits.
People also ask
How do I estimate the cost of a deck?
Multiply the deck's length by its width to get the area in square feet, multiply that by your price per square foot, then add a waste allowance for cuts and offcuts. This tool does all three steps and shows the effective cost per square foot.
Is it cheaper to build a wood or composite deck?
Pressure-treated wood is usually cheaper to install than composite, but composite decking needs far less maintenance over time and can be cheaper across the deck's full life. Enter the per-square-foot price for whichever material you are comparing.
Does deck cost include railings and stairs?
Not automatically. This estimate is based on the deck surface area and your price per square foot. Railings, stairs, footings, and permits are extra, so either fold them into your price per square foot or budget for them separately.
Related calculators
Sources & references
These tools follow our methodology and provide educational estimates only — verify important figures with a qualified professional.