Lumber Yield
Estimating the amount of lumber in a log is done using a log scale. A log scale is a formula with two input variables: the length of the log in feet, and the diameter of the log in inches inside the bark at the smaller end. The output from the formula is a number that is an estimate of the number of board feet of lumber in the log.
A board foot is defined as being 1 inch thick by 12 inches wide by 12 inches long or 144 cubic inches of wood. So, a board 1 inch thick by 12 inches wide by 8 feet long contains 8 bdft.
Of the log scales in common use, the International 1/4 Inch rule comes closest to estimating the lumber yield from a log sawn using a Wood-Mizer sawmill.
Please keep in mind that all log scales assume good quality logs. Defects in logs, such as bend (sweep) or decay will reduce the amount of lumber produced.
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Log Scale: International 1/4 Inch Yield in Board Feet | ||||||
| Diameter (inches) |
Length of Log (feet) | |||||
| 6 | 8 | 10 | 12 | 14 | 16 | |
| 6 | 5 | 10 | 10 | 15 | 15 | 20 |
| 7 | 10 | 10 | 15 | 20 | 25 | 30 |
| 8 | 10 | 15 | 20 | 25 | 35 | 40 |
| 9 | 15 | 20 | 30 | 35 | 45 | 50 |
| 10 | 20 | 30 | 35 | 45 | 55 | 65 |
| 11 | 25 | 35 | 45 | 55 | 70 | 80 |
| 12 | 30 | 45 | 55 | 70 | 85 | 95 |
| 13 | 40 | 55 | 70 | 85 | 100 | 115 |
| 14 | 45 | 65 | 80 | 100 | 115 | 135 |
| 15 | 55 | 75 | 95 | 115 | 135 | 160 |
| 16 | 60 | 85 | 110 | 130 | 155 | 180 |
| 17 | 70 | 95 | 125 | 150 | 180 | 205 |
| 18 | 80 | 110 | 140 | 170 | 200 | 230 |
| 19 | 90 | 125 | 155 | 190 | 225 | 260 |
| 20 | 100 | 135 | 175 | 210 | 250 | 290 |
| 21 | 115 | 155 | 195 | 235 | 280 | 320 |
| 22 | 125 | 170 | 215 | 260 | 305 | 355 |
| 23 | 140 | 185 | 235 | 285 | 335 | 390 |
| 24 | 150 | 205 | 255 | 310 | 370 | 425 |
| 25 | 165 | 220 | 280 | 340 | 400 | 460 |
| 26 | 180 | 240 | 305 | 370 | 435 | 500 |
| 27 | 195 | 260 | 330 | 400 | 470 | 540 |
| 28 | 210 | 280 | 355 | 430 | 510 | 585 |
| 29 | 225 | 305 | 385 | 465 | 545 | 630 |
| 30 | 245 | 325 | 410 | 495 | 585 | 675 |