1x3 actual size, board feet and weight calculator
Nominal lumber sizes describe the rough-sawn dimension before drying and planing. A 1x3 finishes at 0.75 by 2.5 inches, but board feet are still billed on the nominal size.
Douglas fir 530; southern yellow pine 640; spruce 450.
- Board feet per piece
- 2.000
- Total weight
- 15.63
- Weight per piece
- 1.563
- Total linear feet
- 80.0
- Total cost
- 95.00
- Cost per board foot
- 4.750
- Cross-sectional area
- 1210 mm2
Show the working
- Length of each piece = 8
- Number of pieces = 10
- Wood density = 530
- Price per piece = 9.5
- actual_t = 0.75 = 0.75
- actual_w = 2.5 = 2.5
- nominal_t = 1 = 1
- nominal_w = 3 = 3
- Board feet per piece = 1 * 3 * 8 / 12 = 2
- Board feet = 2 * 10 = 20
- actual_volume_m3 = 0.75 * 2.5 * 8 * 12 * 0.0254^3 = 0.002 949 67
- Weight per piece = 0.002 949 67 * 530 = 1.563 33
- Total weight = 1.563 33 * 10 = 15.6333
- Total linear feet = 8 * 10 = 80
- Total cost = 9.5 * 10 = 95
- Cost per board foot = 20 > 0 ? 95 / 20 : 0 = 4.75
- Cross-sectional area = 0.75 * 2.5 * 645.16 = 1209.68
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- board feet = nominal thickness x nominal width x length in feet / 12
- weight = actual cross-section x length x density
Board feet use the nominal size, weight uses the actual size. Mixing them up overstates weight by about 25% on dimensional lumber.
Actual sizes are for dry, surfaced-four-sides softwood. Rough-sawn and green lumber run larger.
Wood weight varies with moisture content: freshly cut softwood can be half again as heavy as kiln-dried.
Nominal against actual
| Measure | Nominal | Actual (in) | Actual (mm) |
|---|---|---|---|
| Thickness | 1 in | 0.75 | 19.0 |
| Width | 3 in | 2.5 | 63.5 |
Frequently asked
What are the actual dimensions of a 1x3?
0.75 by 2.5 inches, or 19.0 by 63.5 mm, surfaced and dry.
Why is a 1x3 not actually 1 by 3 inches?
The nominal size is the green, rough-sawn dimension. Drying shrinks it and planing takes off the rest.