How Much Do You Need: Lumber and Nails

July 29, 2010
A Tree

The amount of lumber and nails you need will depend on your project, but these guidelines will help you determine quantities of each.

Lumber Width and Thickness

When you purchase lumber, you may be surprised to find that a 2 x 4 board is NOT actually 2 inches thick by 4 inches wide in size. Why not? When the board is first cut from the log, it is a true 2 x 4 but the drying process and planing of the board reduce it to a smaller finished 1.5 x 3.5 size.

In the first chart below, we convert common or “nominal” sizes of lumber to the actual dimensions of the finished lumber once it is dried out and milled on each of its four sides to make it flat and straight for building.

  • For example, a board that starts out as a “two-by-four” (nominal size) will end up as a 1-½ by 3-½ (actual size) after it is dried and milled.

Nail Sizes

For larger projects, nails are bought by weight. The nails chart (down the right size) lists different nail sizes and the you the approximate number of nails per pound for that type of nail.

Lumber Measure in Board Feet

Some lumber companies sell lumber by the board foot, a unit of measurement defined as a piece one inch thick (nominal) by one foot wide (nominal) by one foot long (actual) or its equivalent.

In the chart below (at the bottom of the page), we translate common or “nominal” or “true” board sizes into board feet measurements. This should help you to calculate the cost when buying an amount of lumber.

  • For instance, a 2 x 6 also equals one board foot for each foot of length. The formula is T x W x L = Board feet.

Click here to enlarge the Lumber and Nails chart.

Reader Comments

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hi! i find this info helpful.

hi! i find this info helpful. but can i ask for a sample solution for this? just to make sure i interpreted/used the table correctly. :) hope to hear from you

Hi, Mae, We added text above

The Editors's picture

Hi, Mae,
We added text above the chart to try to give more explanation. Here's a sample of how to use the information for a project:
Let's take the classic 2 x 4 board.
As the chart above shows, this board is actually 1-1/2 x 3-1/2 once the board is dried and milled into a plank and finished lumber.
So, let's say you wish to build a deck of 2 x 4s and you want it to be 10-feet-wide, and you decided to have quarter-inch spacing between boards.
With quarter-inch spacing, the board plus the space equals 3.75 inches.
Multiple the width of 10 feet x 12 inches (which equals one foot) and that equals 120 inches.
Divide 120 inches by 3.75 to equal 32 boards across.
I hope this helps! –Your OFA staff