Deck Cost Calculator
Estimate a deck budget from your installed price per square foot, with a contingency buffer for the extras. There is no built-in price list — you supply the rate from your quote or material list.
Calculator
At $35.00/sq ft installed over 200 sq ft, a deck runs about $7,700.00 with a 10% buffer. Composite vs pressure-treated, height and railings change the price — get itemized written quotes.
Deck contractors quote by the finished square foot, so a fast budget is just that rate times your deck area, plus a cushion. Keeping the price as your input means the estimate works for a budget pressure-treated deck and a high-end composite build alike — only the rate changes.
Enter the square footage and the installed price from a real bid (or your material cost per square foot for a DIY job) and the tool grows it by a contingency to cover the parts a flat rate glosses over.
Formula
The estimate is the deck area at your rate, grown by the contingency:
total = (area_sqft × price_per_sqft) × (1 + contingency%)
The contingency absorbs the things a flat per-square-foot rate averages out: footing depth, deck height, railing style, stairs and any demolition. Ten percent is a sensible default; raise it for a tall or complex deck.
Worked example
A 200 sq ft deck at $35/sq ft installed with a 10% contingency:
- Decking: 200 × $35 = $7,000
- Plus 10% contingency: $7,000 × 1.10 = $7,700
So about $7,700 on your numbers. Composite versus pressure-treated, deck height, railings and stairs all swing the per-square-foot rate, so line up itemized quotes before you commit.
What drives deck cost
Material. Pressure-treated pine is the least expensive decking; cedar and hardwoods sit in the middle; capped composite and PVC cost the most up front but skip the staining. Because you enter the rate, switching materials is just a new number — get a per-square-foot figure for each option you are weighing.
Height, stairs and railings. A ground-level platform is far cheaper per square foot than a raised deck that needs tall posts, bracing, a long stair run and code-compliant guardrail. Those are exactly the extras the contingency is meant to catch when you only have a rough rate.
Footings and demolition. Deep frost footings, hard or rocky soil, and tearing out an old deck all add cost beyond the decking itself. If your quote itemizes them, you can trim the contingency; if not, leave the buffer higher.
To turn this budget into a material list, size the boards with the deck board calculator and the concrete for the footings with the post-hole concrete calculator.