Lumber Dimensions Chart Board Feet | The Old Farmer's Almanac

How Much Do You Need: Lumber and Nails

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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 1-1/2 by 3-1/2 (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.

About The Author

Tom Dvorak

Tom Dvorak, a civil engineer, also writes for Family Handyman about DIY home improvement. Read More from Tom Dvorak

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