Board foot examples, worked

Nine boards worked out the way the calculator does them, then a short list with a waste allowance. Each shows what to type, the arithmetic and the answer. Board feet are shown to two decimals, and a whole number is left whole. A cost is worked from the unrounded board feet, so it can be a cent off the two-decimal figure times the price.

1. 1″ (4/4) × 6″ × 8′

  • Type: thickness 4/4, width 6, length 8.
  • Working: 1 in × 6 in × 8 ft ÷ 12 = 4 board feet.

2. 2″ (8/4) × 8″ × 10′

  • Type: thickness 8/4, width 8, length 10.
  • Working: 2 in × 8 in × 10 ft ÷ 12 = 13.33 board feet.

3. 1¼″ (5/4) × 11¼″ × 10′, 3 boards

  • Type: thickness 5/4, width 11 1/4, length 10, 3 boards, price 6.00.
  • Working: 1¼ in × 11¼ in × 10 ft ÷ 12 × 3 = 35.16 board feet.
  • Cost: at $6.00 a board foot, $210.94, from the unrounded 35.15625 board feet.

4. 2×4 (1½″ × 3½″ actual) × 8′

  • Type: thickness 2, width 4, length 8.
  • Working: 2 in × 4 in × 8 ft ÷ 12 = 5.33 board feet.
  • The calculator adds: A store 2×4 is really 1½″ × 3½″. The price uses 2 × 4.

5. 1½″ × 3½″ × 8′

  • Type: thickness 1 1/2, width 3 1/2, length 8, and choose to count what you measured.
  • Working: 1½ in × 3½ in × 8 ft ÷ 12 = 3.50 board feet.
  • The calculator adds: A store 2×4 is really 1½″ × 3½″. The price uses what you measured.

6. ½″ × 12″ × 8′

  • Type: thickness 1/2, width 12, length 8.
  • Working: 1 in × 12 in × 8 ft ÷ 12 = 8 board feet.
  • The calculator adds: Boards under 1 inch are priced as 1 inch thick, so this is 8 board feet, not 4.

7. 2×6 (1½″ × 5½″ actual) × 12′, 6 boards

  • Type: thickness 2, width 6, length 12, 6 boards.
  • Working: 2 in × 6 in × 12 ft ÷ 12 × 6 = 72 board feet.
  • The calculator adds: A store 2×6 is really 1½″ × 5½″. The price uses 2 × 6.

8. 1″ (4/4) × 7¼″ × 8′

  • Type: thickness 4/4, width 7 1/4, length 96".
  • Working: 1 in × 7¼ in × 8 ft ÷ 12 = 4.83 board feet.

9. 1″ (4/4) × 6″ × 8′

  • Type: thickness 4/4, width 6, length 8, price 10.69.
  • Working: 1 in × 6 in × 8 ft ÷ 12 = 4 board feet.
  • Cost: at $10.69 a board foot, $42.76, from the unrounded 4 board feet.

10. A short list with a waste allowance

Three kinds of board go on one list, each with its own price.

  • 2 boards: 2″ (8/4) × 8″ × 10′, 26.67 board feet, $285.07
  • 4 boards: 1″ (4/4) × 6″ × 8′, 16 board feet, $86.88
  • 6 boards: 2×4 (1½″ × 3½″ actual) × 8′, 32 board feet, $38.40

Total: 74.67 board feet (12 boards), $410.35. Board feet are added unrounded, each line’s money is worked from its unrounded board feet, and the money is added in whole cents per line.

With a 10% allowance the calculator says: Net 74.67 bd ft, with 10% waste 82.13 bd ft, $451.42

Check your own

Put the same numbers in the calculator and compare. The formula behind every line is on the formula page.

How this was checked

The numbers on this page come from a port of the Board Foot Calculator iPhone and iPad app’s engine, and an automated test compares them with the app’s own code on well over a hundred thousand inputs (last run ). Statements about lumber are quoted from the USDA Forest Products Laboratory’s Wood Handbook and the American Softwood Lumber Standard, linked where they appear. Your lumberyard’s ticket is what you pay, so ask how it counts a board. If something here is wrong, tell us at a@noshu.net.