Deck Board Calculator

Estimate how many deck boards you need for a deck surface, with cost.

Reviewed Oct 22, 20262 cited sources (BEA, manufacturer specs and NIST)How we calculate

Adjust prices for your state or ZIP (optional)
Know your local prices? Enter them here (optional)

Your state, ZIP and prices are saved only in this browser on this device. Your ZIP never leaves your browser. We don't use store data; the adjustment is a state-level approximation from public U.S. Bureau of Economic Analysis (BEA) data, not a local quote.

Slider runs 0 ft to 50 ft; type any amount in the box.

Slider runs 0 ft to 50 ft; type any amount in the box.

A nominal 6-inch board is 5-1/2 in wide dry dressed under NIST PS 20 (see sources).
Extra material for cuts, breakage and mistakes. Our rule of thumb, not from a published standard; adjust to taste.
Example price only, not checked against a published source; enter what your store charges.
Results update as you type.

Boards to buy

29 boards

Rows of boards
26
Estimated decking cost
$725.00

Rough estimate, not a guarantee. Actual costs vary by supplier, location and project.

Estimate only. Not 100% accurate or guaranteed. Rough estimate, not a guarantee and not financial advice. Actual costs vary by supplier, location and project. Check local prices, product labels and your own measurements before you buy, and get quotes or check with a qualified pro for structural, electrical or permitted work.

Material quantities and prices are rough estimates, not a guarantee and not financial advice. Check product labels, local codes and your own measurements before you buy.

How it works

Surface boards only. Framing, fasteners and railings are extra. Follow the board maker's gap guidance.

The formula

  • Rows = ⌈width × 12 ÷ (board width + gap)⌉
  • Boards = ⌈rows × (length ÷ board length) × (1 + extra %)⌉
  • Cost = boards × price per board

How to use this calculator

  1. Measure the deck.
  2. Enter board size and gap.
  3. Enter your price per board.

Frequently asked questions

Why is a 6-inch board 5.5 inches?

Lumber is sold by nominal size; the actual dressed size is smaller (see sources).

Sources

  1. NIST Voluntary Product Standard DOC PS 20-25, American Softwood Lumber Standard: a nominal 6-inch board is 5-1/2 in wide dry dressed (checked Oct 22, 2026)
  2. BEA: Regional Price Parities by State and Metro Area: state goods price levels used for the optional regional adjustment (checked Oct 22, 2026)

Sources last checked Oct 22, 2026Written and reviewed by the Project Cost Math team against the sources above.How we calculate

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