Ask what a deck costs and the honest answer is a question back: walking on what, and how far off the ground? The calculator above prices square footage against a material rate, which is exactly how the real quote starts.
The frame doesn’t care what you walk on
Under pressure treated, cedar, or composite decking sits the same skeleton: footings, posts, beams, joists, hangers. The framing cost barely moves. That is why material choice is the whole swing between the example rates of $40 per square foot for pressure treated, $50 for cedar, and $60 for composite.
Put that on a 12 by 16 deck, which is 192 square feet:
- Pressure treated at $40: $7,680
- Cedar at $50: $9,600
- Composite at $60: $11,520
Same frame, same footprint, nearly four grand of spread. Quote all three and let the customer pick their lane. The material conversation is covered in wood vs composite deck.
Square footage misses two things
Railing runs by the foot, not the square foot. A 12 by 16 deck and an 8 by 24 deck are both 192 square feet, but the long skinny one carries more railing. Railing is posts, balusters, and top-rail labor, and it is where a square-footage-only rate quietly leaks money. Know how much rail your rate assumes, and adjust when the shape is unusual.
Height changes everything. A deck a step off the grass needs modest footings and no guardrail. The same footprint outside a walkout second story needs engineered footings, longer posts, bracing, code guardrails, and a full stair run. Stairs price cleanest per step, the example rate above uses $150 a step, because a 6-step run and a 14-step run are very different days.
From walkthrough to number in the driveway
A deck quote has maybe five inputs: footprint, material, height, stairs, tear-out if there is an old deck coming down first. That is a calculator job, not an evening-at-the-desk job. PriceDesk runs this calculator with your rates per material, your stair price, and your add-ons, so the itemized number is ready while you are still standing in the yard.
The full method, building the rate from lumber list to margin, is in how to price a deck build. The rates on this page are examples to show the math. Load your own in about five minutes with the free 14-day trial.