Calculate deck square footage from length and width, multiple deck sections, or known area. Estimate decking boards, railing length, joists, waste, material quantity, and project cost.
Rectangular deck mode:
The calculator multiplies deck length by deck width to estimate square footage and perimeter.
Multiple sections mode:
The calculator multiplies one section area by the number of same-size sections.
Known area mode:
The calculator starts from your known deck square footage and estimates material quantity, railing, waste, and cost.
Board coverage mode:
The calculator estimates total coverage from board length, board width, and known board count.
A deck area calculator helps estimate square footage for wood decks, composite decks, deck tiles, stain, sealant, railing, joists, and deck material planning.
It can help calculate deck area, perimeter, railing length, board quantity, joist estimates, waste, and estimated project cost.
Your result shows deck area, perimeter, estimated railing length, area with extra waste, deck boards or material units needed, estimated joist count, and estimated project cost.
Multiply deck length by deck width. For example, a 20 foot by 14 foot deck has an area of 280 square feet.
Divide the deck area with waste by the coverage of one deck board. The calculator can use either coverage per unit or board length and width to estimate board quantity.
Many deck projects use 10% extra material. Complex layouts, diagonal boards, picture-frame borders, stairs, and angled cuts may need more.
Use the deck perimeter, then subtract openings such as stairs or entry points. If railing is only on some sides, use the railing side selector.
For a flat rectangular deck, deck area and deck surface area are usually the same. Stairs, benches, fascia, railings, and multi-level sections may require separate measurements.