Linear feet calculator for trim, lumber and boards
A 12 by 12 ft room has 48 linear feet of wall at the floor. So it takes 48 feet of baseboard before the doorways come out. That is 6 pieces of 8 ft stock or 3 of 16 ft.
The three jobs this calculator does
The first is addition: a list of pieces with their lengths and how many of each, typed in feet and inches. The total comes in feet, yards and meters. That covers trim, fence rails, pipe, cable, edging and anything else bought by length. The second is the conversion builders need most. It turns the square footage of a floor, wall or deck into the linear feet of boards it takes. That depends on how wide each board is. The third runs the other way, telling you how much area a pile of boards will cover. Under the options, a stock length turns the total into pieces to buy and a nominal size gives board feet. A price per foot gives the bill.
Linear feet = sum of (length in feet × count). Linear feet from area = square feet × 12 ÷ board width in inches. Board feet = thickness (in) × width (in) × length (ft) ÷ 12.
Board face widths and how far one linear foot goes
Nominal lumber is smaller than its name. The face width that actually covers the wall or floor is what the conversion uses.
| Nominal size | Actual face width | Square feet covered per linear foot | Linear feet per 100 square feet |
|---|---|---|---|
| 1x3 | 2 1/2 in | 0.21 | 480 |
| 1x4, 2x4 | 3 1/2 in | 0.29 | 343 |
| 1x6, 5/4x6, 2x6 | 5 1/2 in | 0.46 | 218 |
| 1x8 | 7 1/4 in | 0.60 | 166 |
| 1x10 | 9 1/4 in | 0.77 | 130 |
| 1x12 | 11 1/4 in | 0.94 | 107 |
Tongue-and-groove and shiplap boards cover less than their face width because the tongue disappears into the joint. Use the maker's "coverage width" when it prints one.
Baseboard and shoe molding for two rooms
A 12 by 14 ft bedroom has 52 ft of wall. It has a 3 ft door and a 5 ft closet opening, so the baseboard run is 44 ft. The 10 by 11 ft office next to it has 42 ft of wall and one 3 ft door, 39 ft of baseboard. Together that is 83 linear feet of baseboard and the same again of shoe molding, 166 linear feet in all. With 10% extra for miters the order is 183 feet. In 16 ft sticks that is 12 pieces. Type the per-foot price from your store's shelf tag into the price box, and the bill for the 183 feet appears on the list. That is a better check than any national average, because trim prices swing with the profile and the wood.
Measuring for a run of trim or fence
Measure each wall or fence section separately and write them down before adding, because a single long tape pull around corners drifts. For baseboard, measure at floor level and note each opening with its width. For crown molding, measure at the ceiling; rooms are rarely the same size top and bottom. For fences, measure the line post to post and add the gates separately, since gate kits are sold as units. Round each piece up to the next stock length when a wall is longer than one stick. You can also plan the joint over a stud with a scarf cut.
Buying by the piece or by the foot
Home centers sell most trim by the piece in 8, 10, 12 and 16 ft lengths. Lumber yards often quote the same trim per linear foot. A per-foot price looks cheaper until the cut-offs are counted: a 9 ft wall from 8 ft stock wastes 7 ft of a second piece. Put the stock length into the options and the calculator shows the pieces that actually cover your list. That is the number to compare prices on.
Questions about linear feet
What is a linear foot?
One linear foot is a length of 12 inches; the width and thickness of the piece are not counted. A 10 ft long board is 10 linear feet whether it is a 1x2 or a 2x12. Lumber yards, trim suppliers, fence builders and countertop shops all price by the linear foot because the width is fixed by the product.
How do I calculate linear feet?
Measure each piece end to end, convert inches to feet by dividing by 12, and add the pieces together. Three 8 ft boards and two 12 ft boards are 24 + 24 = 48 linear feet. For a room, add the four wall lengths. For a fence, measure along the fence line.
How many linear feet are in a square foot?
It depends on the width of the board. Divide the square feet by the board's face width in feet. For example, 100 square feet of 5 1/2 in deck boards is 100 ÷ 0.458 = 218 linear feet. The same area in 3 1/2 in boards is 343 linear feet. There is no fixed answer without the width, which is why the calculator asks for it.
How do I convert linear feet to square feet?
Multiply the linear feet by the board width in feet. 200 linear feet of 7 1/4 in shiplap covers 200 × 0.604 = 121 square feet. Leave the gaps between boards out of the width if the boards butt together. Include a gap if they are spaced, as deck boards are.
What is the difference between linear feet and board feet?
Linear feet measures length only. A board foot is volume: a piece 1 inch thick, 12 inches wide and 12 inches long. That is thickness × width × length in inches ÷ 144, or in the usual form, thickness (in) × width (in) × length (ft) ÷ 12. A 2x6 that is 10 ft long is 10 linear feet and 10 board feet. A 2x12 of the same length is 10 linear feet but 20 board feet. Hardwood is sold by the board foot, framing lumber and trim by the piece or the linear foot.
How many linear feet of baseboard for a room?
Add the wall lengths, then take out each doorway and any run of built-in cabinets. A 12 by 14 ft room is 52 linear feet. With one 3 ft door and a 6 ft closet opening it needs 43 feet of baseboard. Add 10% for miters and the odd bad stick, and buy lengths that let you run each wall without a joint where you can.
2 source documents
- Ohio State University Extension, Forest Products Terminology, F-85 (board foot: 12 in long, 12 in wide and 1 in thick). Read 2 November 2026.
- NIST and the American Lumber Standard Committee, Voluntary Product Standard PS 20-20, American Softwood Lumber Standard, Table 3 (dressed widths of boards). Read 2 November 2026.