How Many Board Feet Are in a 2x4?

A 2x4x8 is 5.33 board feet. That is the number most people are after, so there it is up front.

Here is how you get it. Board feet run off the nominal size, so a 2x4 counts as a full 2 inches by 4 inches even though the planed stud measures closer to 1.5 by 3.5.

The formula

Two ways to write the same thing:

• board feet = (thickness × width × length_in) / 144
• board feet = (thickness × width × length_ft) / 12

For a 2x4x8, use the second one since your length is already in feet.

(2 × 4 × 8) / 12 = 64 / 12 = 5.33 board feet

Thickness and width stay in inches, length stays in feet, and the 12 does the conversion. Both formulas land on the same answer, so pick whichever matches the numbers in front of you. There is more detail on the setup in how to calculate board feet if you want to see it worked a few more ways.

Board feet for a 2x4 at common lengths

Same formula, just swap the length. Here is a 2x4 across the lengths you actually buy at the yard.

2x4 length	Formula	Board feet
8 ft	(2 × 4 × 8) / 12	5.33
10 ft	(2 × 4 × 10) / 12	6.67
12 ft	(2 × 4 × 12) / 12	8.00
14 ft	(2 × 4 × 14) / 12	9.33
16 ft	(2 × 4 × 16) / 12	10.67

Notice the 12 ft stud lands on a clean 8.00. That happens because 2 × 4 = 8, and dividing by 12 then multiplying by 12 ft cancels out. Handy check if you ever want to sanity test the math in your head. Want other dimensions worked out the same way? The board foot chart has the full grid.

Nominal vs actual on a 2x4

This trips people up, so it is worth being clear. A 2x4 is not actually 2 inches by 4 inches. Once it comes off the saw green and gets planed down and dried, a modern 2x4 measures about 1.5 by 3.5 inches.

But board feet are always figured at the nominal size. You use 2 and 4 in the formula, not 1.5 and 3.5. The nominal number is the rough-sawn size the board started as, and that is the standard everyone prices and tallies against.

So even though your finished stud is smaller than its name, its board-foot count still uses the big numbers. If you plug in 1.5 × 3.5 you will get a lower answer and it will not match what the yard charges you. Stick with nominal. There is a fuller breakdown in what is a board foot if the nominal thing still feels backwards.

Totaling a framing order

Board feet matter most when you are buying in bulk and the price is quoted per thousand board feet, or when you just want to know how much lumber a wall eats.

Say you are framing a wall and need 40 studs, all 2x4x8. Each one is 5.33 bf.

40 × 5.33 = 213.2 board feet

Now add a couple of 2x4x16 plates, top and bottom, running the length of the wall. Two of those at 10.67 bf each is 21.34 bf. Total order so far:

213.2 + 21.34 = 234.54 board feet

The move is always the same. Get the board feet for one piece of each size, multiply by how many of that piece you need, then add the groups together. Mixed lengths and mixed dimensions all fold into one total that way.

If you are running a real cutlist with a bunch of different sizes, punch it into the board foot calculator instead of doing it by hand. You enter each line, it tallies the whole order, and you get one number to hand the yard or drop into a bid.

Quick recap

• A 2x4x8 is 5.33 board feet.
• Use (thickness × width × length_ft) / 12 with nominal sizes.
• A 2x4 measures about 1.5 × 3.5 after planing, but you still figure it as 2 × 4.
• Total an order by pricing one piece per size, multiplying by quantity, and adding the groups.