Nominal 2×4 → Actual 1½" × 3½"

What size is a 2×4, really?

Q: What size is a 2×4, really?

A nominal 2×4 actually measures 1½" × 3½". The difference comes from milling and drying — the board starts closer to its named size, then shrinks as it's surfaced smooth and dried to standard moisture content.

A 2×4 is sold and labeled as 2×4, but it actually measures 1½" × 3½". The difference comes from milling and drying — the board starts closer to its named size, then shrinks as it's surfaced smooth and dried to standard moisture content.

DASHED = WHAT IT'S CALLED · SOLID = WHAT YOU GET

A 2×4 is actually 1½" × 3½" — not 2×4.

What a 2×4 is actually used for

Wall studs, general framing, workbenches

Good to know before you buy

Standard 16" on-center stud spacing is planned around the actual 1½" width, not the nominal 2" — always lay out framing from actual dimensions.

How many 2×4s do you need?

USES ACTUAL WIDTH, NOT NOMINAL

Boards to span a width

Calculates how many 2×4 boards, laid edge to edge, are needed to cover a given width — using the real 3½" width plus any gap you leave between boards.

Width to cover (ft)

Gap between boards (in)

Board feet

Uses the actual 1½" × 3½" dimensions to calculate true board feet for pricing or ordering.

Length (ft)

Quantity

2×4 vs. every other size

FULL REFERENCE CHART

Nominal Size	Actual Size	Actual (decimal)

Other sizes

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