Mouldings: Nominal vs. Actual Lumber Sizes

Softwood Lumber Dimensions: 

Softwood lumber is generally used for framing walls and floors. In the United States, softwood lumber is governed by the National Institute of Standards American Softwood Lumber Standard (PS 20).

 

North American Standard “1-by” Lumber

NOMINAL SIZE          ACTUAL SIZE            ACTUAL SIZE

(INCHES)                   (INCHES)                   (MM)                

1 x 2                            3/4 x 1-1/2                   19 x 38

1 x 3                            3/4 x 2-1/2                   19 x 64

1 x 4                            3/4 x 3-1/2                   19 x 89

1 x 6                            3/4 x 5-1/2                   19 x 140

1 x 8                            3/4 x 7-1/4                   19 x 184

1 x 10                          3/4 x 9-1/4                   19 x 235

1 x 12                          3/4 x 11-1/4                 19 x 286

 

North American Standard “2-by” Lumber

NOMINAL SIZE          ACTUAL SIZE            ACTUAL SIZE

(INCHES)                   (INCHES)                   (MM)                

2 x 2                            1-1/2 x 1-1/2               38 x 38

2 x 3                            1-1/2 x 2-1/2               38 x 64

2 x 4                            1-1/2 x 3-1/2               38 x 89

2 x 6                            1-1/2 x 5-1/2               38 x 140

2 x 8                            1-1/2 x 7-1/4               38 x 184

2 x 10                          1-1/2 x 9-1/4               38 x 235

2 x 12                          1-1/2 x 11-1/4             38 x 286

 

North American Standard 3-by Lumber

NOMINAL SIZE          ACTUAL SIZE            ACTUAL SIZE

(INCHES)                   (INCHES)                   (MM)                

3 x 3                            2-1/2 x 2-1/2               64 x 64

3 x 4                            2-1/2 x 3-1/2               64 x 89

3 x 6                            2-1/2 x 5-1/2               64 x 140

3 x 8                            2-1/2 x 7-1/4               64 x 184

3 x 10                          2-1/2 x 9-1/4               64 x 235

3 x 12                          2-1/2 x 11-1/4             64 x 286

 

North American Standard 4-by Lumber

NOMINAL SIZE          ACTUAL SIZE            ACTUAL SIZE

(INCHES)                   (INCHES)                   (MM)                

4 x 4                            3-1/2 x 3-1/2               89 x 89

4 x 6                            3-1/2 x 5-1/2               89 x 140

4 x 8                            3-1/2 x 7-1/4               89 x 184

4 x 10                          3-1/2 x 9-1/4               89 x 235

4 x 12                          3-1/2 x 11-1/4             89 x 286

 

North American Standard 6-by Lumber

NOMINAL SIZE          ACTUAL SIZE            ACTUAL SIZE

(INCHES)                   (INCHES)                   (MM)                

6 x 6                            5-1/2 x 5-1/2               140 x 140

 

North American Standard 8-by Lumber

NOMINAL SIZE          ACTUAL SIZE            ACTUAL SIZE

(INCHES)                   (INCHES)                   (MM)                

8 x 8                            7-1/4 x 7-1/4               184 x 184

 

 

Softwood Lumber Lengths

Softwood lumber comes in a number of standard lengths as listed in the table below.

 

LENGTH IN FEET      LENGTH IN INCHES            LENGTH IN METERS

6 feet                           72 inches                                1.829 meters

8 feet                           96 inches                                2.438 meters

10 feet                         120 inches                              3.048 meters

12 feet                         144 inches                              3.658 meters

14 feet                         168 inches                              4.267 meters

16 feet                         192 inches                              4.877 meters

18 feet                         216 inches                              5.486 meters

20 feet                         240 inches                              6.096 meters

22 feet                         264 inches                              6.706 meters

24 feet                         288 inches                              7.315 meters