This section is from the book "The Building Trades Pocketbook", by International Correspondence Schools. Also available from Amazon: Building Trades Pocketbook: a Handy Manual of reference on Building Construction.
Radii of gyration given correspond to directions of the arrowheads.

Size. Inches. | Thickness. Inches. | Radii of Gyration. | |||
r0. | r1 | r2. | r3 | ||
7 X3 1/2 | 7/16 | .95 | 3.37 | 3.56 | 3.66 |
6 X4 | 7/8 | 1.19 | 2.94 | 3.13 | 3.23 |
6 X4 | 3/8 | 1.17 | 2.74 | 2.92 | 3.02 |
5 X3 1/2 | 3/4 | 1.01 | 2.39 | 2.58 | 2.68 |
5 X3 1/2 | 3/8 | 1.02 | 2.27 | 2.45 | 2.55 |
5 X3 | 3/4 | .86 | 2.50 | 2.69 | 2.79 |
5 X3 | 5/16 | .85 | 2.33 | 2.51 | 2.61 |
4 1/2X3 | 3/4 | .86 | 2.18 | 2.38 | 2.46 |
4 1/2X3 | 5/16 | .87 | 2.06 | 2.25 | 2.33 |
4 X3 1/2 | 3/4 | 1.05 | 1.85 | 2.04 | 2.14 |
4 X3 1/2 | 5/16 | 1.07 | 1.73 | 1.91 | 2.00 |
4 X3 | 5/8 | .83 | 1.84 | 2.03 | 2.13 |
4 X3 | 5/16 | .89 | 1.79 | 1.97 | 2.07 |
3 1/2X3 | 5/8 | .87 | 1.57 | 1.76 | 1.87 |
3 1/2X3 | 5/16 | .90 | 1.53 | 1.71 | 1.81 |
3 1/2X2 1/2 | 9/16 | .72 | 1.66 | 1.85 | 1.95 |
3 1/2 X 2 1/2 | 1/4 | .74 | 1.58 | 1.76 | 1.86 |
3 X2 1/2 | 9/16 | .73 | 1.40 | 1.59 | 1.69 |
3 X2 1/2 | l/4 | .75 | 1.32 | 1.49 | 1.60 |
3 X2 | 1/2 | .55 | 1.42 | 1.62 | 1.72 |
3 X2 | 1/4 | .57 | 1.39 | 1.57 | 1.68 |
2 1/2X2 | 1/2 | .56 | 1.16 | 1.35 | 1.46 |
2 1/2X2 | 3/16 | .60 | 1.10 | 1.28 | 1.39 |
 
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