Nominal ≠ Actual

A 2×4 isn't 2 inches by 4 inches.

It's actually 1½" × 3½". Lumber is named by its rough-cut size before drying and planing shrink it down. Pick a size below to see the real dimensions — no jargon, no guessing.

NOMINAL 4" ACTUAL 3½" ½" lost to milling + drying
DASHED = WHAT IT'S CALLED · SOLID = WHAT YOU GET

Pick a size

TAP A SIZE FOR ITS ACTUAL DIMENSIONS
Nominal Size (what it's called)
2×4
Actual Size (what you measure)
1½" × 3½"

View full guide & calculators for this size →

Project calculators

USES ACTUAL DIMENSIONS, NOT NOMINAL

Deck board coverage

How many boards to cover a given deck area, accounting for actual board width and gap spacing.

Board feet calculator

Uses actual thickness and width to compute true board feet for pricing or ordering.

Full reference chart

DIMENSIONAL SOFTWOOD LUMBER · INCHES
Nominal SizeActual SizeActual (decimal)