Construction

Decking Calculator

Calculate boards, joists, screws, and costs for your deck project

Quick Answer:A 16x12 ft deck requires approximately 46 standard 5.5"x16' composite boards and 10 joists in 2026. Material costs range from $960-1,440 for pressure-treated wood to $1,536-2,304 for composite decking.

Deck Dimensions

Deck Length (ft)

Deck Width (ft)

Board Width (inches)

Board Length (ft)

Joist Spacing (inches)

Total Boards

Calculating... deck boards

Deck Area

Joists Needed

Screws

Estimated Cost

Visual Comparison

Deck Boards --

Wood Cost ($5-8/sqft) --

Composite Cost ($8-12/sqft) --

Expert Insight 2026 Pro Tip

In 2026, composite decking offers 25-50 year warranties versus 10-15 years for pressure-treated wood, making the higher upfront cost worthwhile for many homeowners. Use hidden fastener systems for composite decking to achieve a clean, screw-free surface -- they cost about $0.50 more per square foot but dramatically improve appearance. Always leave 1/8" to 3/16" gaps between boards for drainage and thermal expansion. Most municipalities require building permits for decks over 200 square feet or 30 inches above grade, with inspections at the footing, framing, and final stages.

Frequently Asked Questions About Decking

How do I calculate how many deck boards I need?

To calculate deck boards, first determine the deck area (length times width). Then calculate each board's coverage area by multiplying the board width (in feet) by the board length. For standard 5.5-inch wide boards, convert to feet (0.458 ft) and multiply by the board length. Divide the total deck area by the coverage area per board, then round up. For a 16x12 ft deck using 5.5-inch by 16-foot boards, each board covers 7.33 sq ft. The 192 sq ft deck divided by 7.33 equals approximately 27 boards. Add 10-15% for waste from cuts and defective boards.

How many joists do I need for a deck?

To calculate deck joists, divide the longer deck dimension (in inches) by the joist spacing (typically 16 inches for wood decking or 12 inches for diagonal patterns), then add 1 for the end joist. For a 16-foot long deck with 16-inch spacing, that is 192 inches divided by 16, plus 1, equaling 13 joists. However, most composite decking manufacturers require 12-inch joist spacing for residential applications. Double joists are needed where deck boards butt together end-to-end. Use pressure-treated 2x8 or 2x10 lumber for joists depending on span requirements.

How much does it cost to build a deck in 2026?

In 2026, deck construction costs range from $15-45 per square foot depending on materials and complexity. Pressure-treated wood decking costs $5-8 per square foot for materials, while composite decking ranges from $8-12 per square foot. Premium PVC and capped composite can reach $12-18 per square foot. For a standard 16x12 ft deck (192 sq ft), material costs range from $960 for basic wood to $2,300 for mid-range composite. Professional installation adds $15-25 per square foot for labor. Total installed costs for a simple ground-level deck run $5,000-10,000, while elevated decks with railings and stairs can exceed $15,000-25,000.