Enter your deck size and material. You’ll get the number of deck boards, joists and screws, and a side-by-side cost comparison of wood and composite.
How the deck calculator works
Standard deck boards are 5½ inches wide and are laid with a 3/16-inch gap, so each row covers about 5.69 inches. Joists run out from the house every 16 inches.
Boards = rows × (deck length ÷ board length), each rounded up
Joists = deck length (in) ÷ 16 + 1
Worked example: a 16 × 12 ft deck
A 12-foot-deep deck needs 26 rows of boards. With 16-foot boards that is 26 boards, plus 13 joists and about 680 screws. In pressure-treated wood at $35 per sq ft installed, the 192 sq ft deck costs $6,720. Adding 28 feet of railing at $40 per foot brings it to about $7,840.
Deck cost per square foot in 2026
Angi puts the average professionally built deck at $30–$60 per square foot, with a national average project of about $8,250, according to NerdWallet. Labor makes up roughly half of that. Planning ranges by material:
| Decking | Installed per sq ft | Upkeep |
|---|---|---|
| Pressure-treated pine | $25–$45 | Stain or seal every 2–3 years |
| Cedar or redwood | $35–$60 | Seal yearly to keep color |
| Composite | $45–$80 | Wash once or twice a year |
| PVC | $55–$95 | Wash once or twice a year |
Railing is priced separately, usually $20–$80 per foot depending on material. Read more in our deck cost guide.
Frequently asked questions
Is composite decking worth the extra cost?
It often costs about twice as much up front, but you skip yearly staining. If you’ll stay in the home 15+ years, the total cost is often similar.
Do I need a permit for a deck?
Usually, yes, if the deck is attached to the house or more than 30 inches off the ground. Rules vary by city.
How many extra boards should I buy?
About 10% for cuts and boards with defects; 15% for diagonal or picture-frame patterns.
Sources: NerdWallet, citing Angi (2026); 2026 deck cost guides from RemodelAI and Decks.com.
