Deck boards calculator
PROBoard count, joists and screws for a rectangular deck.
Short answer: Boards = width × 12 ÷ (board width + gap). Joists = width × 12 ÷ spacing + 1. 12 ft wide, 5.5" boards + ⅛" gap = 25 boards; 16" o.c. = 10 joists. Enter your measurements above and the deck boards calculator returns the quantity, unit conversions and an estimated cost instantly, in imperial or metric — no sign-up needed.
What do you need to measure?
What is the answer?
Deck boards
26
16 ft each
Joists
10
Deck screws (2/joist)
520
How does the deck boards calculator work?
Boards = width × 12 ÷ (board width + gap). Joists = width × 12 ÷ spacing + 1.
What does a worked example look like?
12 ft wide, 5.5" boards + ⅛" gap = 25 boards; 16" o.c. = 10 joists.
What do people ask most?
›Board gap?
⅛" for wet composite/PT; up to ¼" for dry hardwood.
Which outdoor construction calculator should you use next?
Where can you learn more?
Read field notes on estimating and materials, or browse every calculator we make.
What should you read before you order materials?
Field notes from real jobs that explain the numbers behind this calculator.
How Fast Does a Pool Lose Chlorine? Sun vs. Swimmers Data
Ever wonder if it's the sun or the swimmers burning through your pool chlorine? I tracked free chlorine levels in dozens of client pools to find out. We'll break down the real-world ppm/hour loss rates I've measured, so you can stop guessing and get your chemical dosing right.
How Much Mulch to Use? A Pro's Guide to Compaction & Top-Offs
Every landscaper says 'apply 2-3 inches of mulch,' but that advice is incomplete. Based on measurements from my job sites, I'll explain the hidden factor of mulch compaction—why your fresh 3-inch layer can shrink by 50% in a season—and how to choose and apply materials for lasti…
Why Paver Patios Heave: A Freeze-Thaw Base Prep Guide
I've torn out more heaved paver patios than I can count. Frost heave isn't magic; it's physics. The difference between a 20-year patio and a 2-year disaster in cold climates comes down to one thing: managing water in the base. Here’s my field-tested method for building a paver b…
Sod vs. Seed Cost: Finding the Break-Even Point for Your Lawn
Everyone says seed is cheaper than sod, but is it always? As a landscape estimator, I break down the real-world costs of labor, materials, and prep to find the exact square footage where the math flips. For small lawns, sod is often the smarter financial choice.