Lumber – Nominal vs Actual Dimensions

Lumber is cut to a standard length, width, and depth. However, there is a difference between nominal and actual lumber dimensions.

The standard for converting nominal to actual dimensions is as follows:

  • Subtract ¼ inches for dimensions under 2 inches
  • Subtract ½ inches for dimensions from 2 inches to 8 inches
  • Subtract ¾ inches for dimensions equal to or larger than 8 inches

For quick reference, use the following tables to determine the actual lumber dimensions based on the nominal size.

Standard 1 x Lumber

Nominal Size (inches)

Actual Size (inches)

1 x 2

¾  x 1 ½

1 x 3

¾ x 2 ½

1 x 4

¾ x 3 ½
1 x 6

¾ x 5 ½

1 x 8

¾ x 7 ¼

1 x 10

¾ x 9 ¼

1 x 12

¾ x 11 ¼

 

Standard 2 x Lumber

Nominal Size (inches)

Actual Size (inches)

2 x 2

1 ½  x 1 ½

2 x 3

1 ½ x 2 ½

2 x 4

1 ½ x 3 ½
2 x 6

1 ½ x 5 ½

2 x 8

1 ½ x 7 ¼

2 x 10

1 ½ x 9 ¼

2 x 12

1 ½ x 11 ¼

 

Standard 3 x Lumber

Nominal Size (inches)

Actual Size (inches)

3 x 3

2 ½ x 2 ½

3 x 4

2 ½ x 3 ½
3 x 6

2 ½ x 5 ½

3 x 8

2 ½ x 7 ¼

3 x 10

2 ½ x 9 ¼

3 x 12

2 ½ x 11 ¼

 

Standard 4 x Lumber

Nominal Size (inches)

Actual Size (inches)

4 x 4

3 ½ x 3 ½

4 x 6

3 ½ x 5 ½

4 x 8

3 ½ x 7 ¼

4 x 10

3 ½ x 9 ¼

4 x 12

3 ½ x 11 ¼

Let me know if you have any questions and I’ll get back to you as soon as possible.

 

 

 

 

2 comments

  1. Bitsey - Reply

    I nerded out with you! I love your lilting commentary. The information is thorough, helpful, and your humor is delightful. Thank you for sharing your everyday life ideas. 🙂

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