Deck Area Calculator
Add one rectangle for a simple deck, or several for an L-shape or notched layout — then subtract any openings.
Example section shown — edit or add sections below
Multiple-rectangle mode assumes sections do not overlap. Divide your deck into non-overlapping rectangles before entering dimensions.
Net deck area
240 sq ft
- Gross area
- 240 sq ft
- Excluded area
- 0 sq ft
›Calculation details
Gross area is the sum of every section's length × width.
Net area subtracts any exclusions you've added (stair openings, planters, cutouts).
Multiple-rectangle mode assumes sections do not overlap. Divide your deck into non-overlapping rectangles before entering dimensions.
How it works
Gross area is the sum of every rectangular section's length × width. Net area subtracts any exclusions — a stair opening, a planter, or another cutout. This mode assumes your sections don't overlap; split an L-shaped or notched deck into two or more non-overlapping rectangles before entering dimensions.
FAQ
My deck is L-shaped — how do I measure it?
Split it into two rectangles along a straight line, add both as separate sections, and the calculator sums them for you.
Can I subtract a hot tub or built-in planter?
Yes — add it as an exclusion with its own length and width, as long as it's roughly rectangular.