How to use the deck calculator
Enter the deck length along the house and the depth out into the yard, pick the decking material and board length, and add the railing and stair steps you need. The calculator gives you a full installed price range for your state plus the main framing and decking counts for a DIY material list.
Railing is usually only required when the deck is more than 30 inches above the ground, but many homeowners add it anyway. For a deck attached on one side, a typical railing length is the depth × 2 plus the length.
How deck materials are calculated
Deck boards = Rows × (Deck length ÷ Board length) × 1.10
Joists = Deck length (in) ÷ 16 + 1
Footings ≈ one every 8 ft along each beam
Example: a 16 × 12 ft deck with 16 ft boards needs 26 rows of decking, or 29 boards with 10% extra, plus 13 joists at 16 inches on center.
Deck cost per square foot (2026)
| Material | Installed / sq ft | Railing / ft | Lifespan |
|---|---|---|---|
| Pressure-treated pine | $25–$42 | $30–$60 | 15–20 yrs |
| Cedar / redwood | $35–$55 | $40–$70 | 15–25 yrs |
| Composite | $45–$75 | $60–$110 | 25–30+ yrs |
| PVC / capped premium | $55–$85 | $70–$120 | 30–50 yrs |
| Ipe / tropical hardwood | $60–$100 | $70–$130 | 40+ yrs |
Stairs add about $150–$300 per step. Raised and second-story decks cost 10–30% more because of taller posts, bracing, beams and engineering. Built-in lighting, benches and pergolas are extra.
Wood or composite?
Pressure-treated wood is the cheapest to build, but needs cleaning and staining every 2–3 years and eventually splinters and checks. Composite costs about 60–80% more up front but needs only an occasional wash and comes with 25–50 year warranties. Over 20 years the total cost of the two is often close, so composite usually wins for people who don't want maintenance.
Deck cost by state
16×12 ft pressure-treated deck with 40 ft of railing and 3 steps — estimated cost by state. Figures use the same assumptions as the calculator above.
| State | Low | High | vs. US avg |
|---|---|---|---|
| US average | $6,450 | $11,364 | — |
| Alabama | $5,612 | $9,887 | -13% |
| Alaska | $8,063 | $14,205 | +25% |
| Arizona | $6,192 | $10,909 | -4% |
| Arkansas | $5,547 | $9,773 | -14% |
| California | $7,869 | $13,864 | +22% |
| Colorado | $6,644 | $11,705 | +3% |
| Connecticut | $7,353 | $12,955 | +14% |
| Delaware | $6,708 | $11,819 | +4% |
| District of Columbia | $7,418 | $13,069 | +15% |
| Florida | $6,128 | $10,796 | -5% |
| Georgia | $5,870 | $10,341 | -9% |
| Hawaii | $8,514 | $15,000 | +32% |
| Idaho | $6,063 | $10,682 | -6% |
| Illinois | $7,095 | $12,500 | +10% |
| Indiana | $6,128 | $10,796 | -5% |
| Iowa | $6,128 | $10,796 | -5% |
| Kansas | $5,999 | $10,569 | -7% |
| Kentucky | $5,934 | $10,455 | -8% |
| Louisiana | $5,805 | $10,228 | -10% |
| Maine | $6,450 | $11,364 | 0% |
| Maryland | $6,579 | $11,591 | +2% |
| Massachusetts | $7,740 | $13,637 | +20% |
| Michigan | $6,450 | $11,364 | 0% |
| Minnesota | $6,902 | $12,159 | +7% |
| Mississippi | $5,418 | $9,546 | -16% |
| Missouri | $6,321 | $11,137 | -2% |
| Montana | $6,192 | $10,909 | -4% |
| Nebraska | $5,999 | $10,569 | -7% |
| Nevada | $6,708 | $11,819 | +4% |
| New Hampshire | $6,708 | $11,819 | +4% |
| New Jersey | $7,547 | $13,296 | +17% |
| New Mexico | $5,870 | $10,341 | -9% |
| New York | $7,740 | $13,637 | +20% |
| North Carolina | $5,741 | $10,114 | -11% |
| North Dakota | $6,192 | $10,909 | -4% |
| Ohio | $6,257 | $11,023 | -3% |
| Oklahoma | $5,676 | $10,000 | -12% |
| Oregon | $6,837 | $12,046 | +6% |
| Pennsylvania | $6,644 | $11,705 | +3% |
| Rhode Island | $7,095 | $12,500 | +10% |
| South Carolina | $5,676 | $10,000 | -12% |
| South Dakota | $5,805 | $10,228 | -10% |
| Tennessee | $5,805 | $10,228 | -10% |
| Texas | $5,934 | $10,455 | -8% |
| Utah | $6,192 | $10,909 | -4% |
| Vermont | $6,579 | $11,591 | +2% |
| Virginia | $6,192 | $10,909 | -4% |
| Washington | $7,095 | $12,500 | +10% |
| West Virginia | $5,870 | $10,341 | -9% |
| Wisconsin | $6,515 | $11,478 | +1% |
| Wyoming | $5,999 | $10,569 | -7% |
Frequently asked questions
How much does a 16×12 deck cost?
A 16×12 ft (192 sq ft) pressure-treated deck costs about $6,500–$11,400 installed at the US average, including 40 ft of railing and three steps. The same deck in composite costs about $11,500–$19,700.
How many deck boards do I need?
Divide the deck depth in inches by 5.625 (a 5.5 in board plus a gap) to get the rows, multiply by the boards needed per row, then add 10%. A 16×12 deck with 16 ft boards needs about 29 boards.
Is composite decking worth it?
If you plan to stay in the home 10 years or more and dislike maintenance, usually yes. It costs more up front but avoids staining and sealing, and lasts two to three times longer than pressure-treated wood.
Do I need a permit to build a deck?
Most US towns require a permit for decks attached to the house, higher than 30 inches off the ground, or over about 200 sq ft. Check with your local building department.
What joist spacing do I need?
16 inches on center is standard for most decking. Composite boards laid diagonally, and some lighter products, need 12 inches on center — check the manufacturer’s span chart.