Table 4-1

American Standard Lumber Sizes for Stress-graded and Non-stress-graded Lumber for Construction1.
 
Thickness
  
Face width
 
 
           
Meteric
            
Meteric
   
Minimum dressed
nomenclature
    
Minimum dressed
nomenclature
   
   
Item
Nominal
Dry
Green
Dry
Green
Nominal
Dry
Green
Dry
Green
 
  (In)
(In)
(mm)
(In)
(mm)
(mm)
(mm)
  
  (In)
(In)
(mm)
(In)
(mm)
(mm)
(mm)
Boards
1
3/4
19.05
25/32
19.84
 19
20
2
  1-1/2
  38.10
  1-9/16
  39.69
38
39
1-1/4
1
25.40
1-1/32
26.19
 25
26
3
  2-1/2
  63.50
  2-9/16
  65.09
64
66
1-1/2
1-1/4
31.75
1-9/32
32.54
 32
33
4
  3-1/2
  88.90
  3-9/16
  90.49
89
91
5
  4-1/2
114.30
  4-5/8
117.47
114
117
6
  5-1/2
139.70
  5-5/8
142.87
139
143
7
  6-1/2
165.10
  6-5/8
168.28
165
170
8
  7-1/4
184.15
  7-1/2
190.50
185
190
9
  8-1/4
209.55
  8-1/2
215.90
210
216
10
  9-1/4
234.95
  9-1/2
241.30
235
242
11
10-1/4
260.35
10-1/2
266.70
260
267
12
11-1/4
285.75
11-1/2
292.10
285
293
14
13-1/4
336.55
13-1/2
342.90
335
345
16
15-1/4
387.35
15-1/2
393.70
385
395
Dimension
2
1-1/2
  38.10
   1-9/16
  39.69
 38
39
2
  1-1/2
  38.10
  1-9/16
  39.69
38
39
2-1/2
2
  50.80
   2-1/16
  52.39
 51
52
3
  2-1/2
  63.50
  2-9/16
  65.09
64
66
3
2-1/2
  63.50
   2-9/16
  65.09
 64
66
4
  3-1/2
  88.90
  3-9/16
  90.49
89
91
3-1/2
3
  76.20
   3-1/16
  77.79
 76
78
5
  4-1/2
114.30
  4-5/8
117.47
114
117
4
3-1/2
  88.90
   3-9/16
  90.49
 89
91
6
  5-1/2
139.70
  5-5/8
142.87
139
143
4-1/2
4
101.60
   4-1/16
101.19
102
104
8
  7-1/4
184.15
  7-1/2
190.50
185
190
10
  9-1/4
234.95
  9-1/2
241.30
235
242
 12
11-1/4
285.75
11-1/2
292.10
285
293
14
13-1/4
336.55
13-1/2
342.90
335
345
16
15-1/4
387.35
15-1/2
393.70
385
395
                               
Timbers
5 and
    
1/2 less
        
  5 and
    
1/2 less
      
 
greater
    
than
        
  greater
    
than
      
 
   
nominal
              
nominal
      
Source:  USDC 1970; metric values from WWPA (ND).
Example:  A nominal 2 x 4 is a metric 38 x 89, a nominal 4 x 16 is a metric 89 x 387, etc.
1Nominal sizes in the table are used for convenience. No inference should be drawn that they represent actual sizes.