Deck Cost Calculator
What a new deck is likely to cost installed, based on deck size and a per-square-foot rate you can adjust to match quotes in your area.
Result
| Deck area | |
| Rate used | |
| Estimated installed cost |
Units & conversions used
Deck area in square feet; metric areas are converted at 1 m² = 10.7639 ft². Cost is deck surface area (ft²) multiplied by your installed rate per square foot — the convention deck builders use when quoting, because framing, footings and labor are priced into the rate.
Formula & source
Cost range = area(ft²) × low rate … area(ft²) × high rate
Source: area is simple rectangle geometry. The $25–$50/ft² default band reflects commonly published 2025–2026 US pricing for a professionally installed deck; pressure-treated wood tends toward the lower part, composite decking and multi-level designs toward or above the top. It is a budgeting aid, not a quote — decking material, height off the ground, stairs and railings move real prices a lot, so replace the defaults with local quotes whenever you have them.
Worked example (you can verify by hand)
Input: 16 ft × 20 ft deck, rates $25–$50/ft².
- Area: 16 × 20 = 320 ft²
- Low estimate: 320 × $25 = $8,000
- High estimate: 320 × $50 = $16,000
Expected output: estimated installed cost $8,000–$16,000 for a 320 ft² deck.
Limitations — what this cannot do
- One rectangle, one flat rate. Stairs, railings, benches, pergolas and multi-level sections are not itemized — builders often price those separately.
- Height matters: a deck 8 ft off the ground needs taller posts, more bracing and often a permit review; a ground-level platform does not. The single rate cannot capture that spread.
- Permits, demolition of an old deck, and difficult yard access are extra. Get itemized local quotes before committing to a budget.
FAQ
How much does a 16×20 deck cost?
320 ft² at the commonly published 2025–2026 installed range of $25–$50/ft² gives $8,000–$16,000. Pressure-treated lumber usually lands lower; composite boards, cable railings and added stairs push toward or past the top. If your quotes fall far outside this band, ask the builder to itemize what is included.
How can I check a contractor's deck quote?
Divide the quote by your deck's square footage to get their $/ft², then compare it with the range above. A quote of $12,800 for a 320 ft² deck is $40/ft² — inside the band. Also confirm the quote states the decking material, footing type, railing, stairs and permit fees; a low headline number often excludes several of those.
What makes one deck cost twice as much as another the same size?
Mainly the surface material (composite can cost several times pressure-treated pine per board), height and footing requirements, railing style, stairs, and built-ins. Two decks with identical footprints can legitimately differ by 2× once those are chosen.
How can I save money on a new deck?
Shrink the footprint (cost is per square foot), choose pressure-treated lumber over composite, keep the design one level with a simple railing, and handle demolition of the old deck yourself if you are able. Getting three quotes in the off-season also tends to help. Estimate your boards first with our deck board calculator so you can compare material costs line by line.