How to convert square feet to linear feet
Linear feet measure length. To convert from square feet you need the width of the material.
The formula
Linear feet = square feet ÷ width of the material in feet
Worked example
Covering 200 square feet with boards 5.5 inches wide (0.458 feet) takes about 436 linear feet.
How to use this calculator
Enter the area you need to cover in square feet, the width of one board or roll and a waste allowance. The calculator converts square feet to linear feet by dividing the area by that width. It shows the linear feet needed with waste, the figure before waste, and how many 8-foot or 12-foot boards that is. Measure the width of the actual material where you can, because the size printed on a label is not always the size that covers the surface.
A shortcut when the width is in inches
Board widths are normally given in inches. This version of the formula saves a step:
Linear feet = square feet × 12 ÷ width in inches
For the example above, 200 × 12 ÷ 5.5 = 436 linear feet.
More examples
The table shows how many linear feet cover the same 200 square feet at different material widths.
| Material width | Linear feet for 200 sq ft |
|---|---|
| 2.25 inches | 1,067 |
| 3.5 inches | 686 |
| 5.5 inches | 436 |
| 7.25 inches | 331 |
| 12 inches | 200 |
| 36 inches (a 3-foot roll) | 67 |
Turning linear feet into a board count
Divide the linear feet by the length of one board and round up. Adding 10% waste to the 436 linear feet above gives about 480 linear feet. With 12-foot boards that is 40 boards. With 16-foot boards it is 30.
Boards laid with a gap
Deck boards are usually spaced apart, so each board covers its own width plus the gap. Use that combined figure as the width. With 5.5 inch boards and a 1/8 inch gap, the width is 5.625 inches, and 200 × 12 ÷ 5.625 = about 427 linear feet.
Going the other way
To find the area a known length will cover, multiply linear feet by the width in feet. 300 linear feet of material 6 inches wide (0.5 feet) covers 150 square feet.
What changes the result
- Width. Narrower material needs more length. Halving the width doubles the linear feet.
- Area. Linear feet rise in step with the square feet you cover.
- Gaps and overlaps. A gap between boards lowers the linear feet needed. An overlap, as with lap siding, raises it, because only the exposed part of each board covers the wall.
- Waste. Cuts at the ends of each run add to the total.
What the result means
The answer is the total running length of material, laid end to end, that covers your area. The main figure includes the waste allowance you entered, and the figure before waste is shown beside it. The board counts assume 8-foot or 12-foot boards, so work out other lengths yourself. Stores often price trim, decking and fencing by the linear foot, so multiplying the result by that price gives a rough material cost. Treat it as an estimate and check quantities with your supplier before you order.
Common mistakes
- Dividing by the width in inches without converting. 200 ÷ 5.5 gives 36, which is far too low.
- Using the nominal size of lumber. Boards are sold by a nominal size, and the actual width is smaller.
- Using the full width of an overlapping board instead of the exposed width.
- Confusing linear feet with board feet. Board feet measure volume and include thickness.
- Ordering with no allowance for cuts.
Related calculators
If you still need the area, start with the square footage calculator. The flooring calculator works in boxes rather than length, and the fence calculator counts posts, rails and pickets from the length of the fence line.
Frequently asked questions
How do I convert the width to feet?
Divide the width in inches by 12.
Should I add waste?
Yes. Add 5% to 10% for cuts.
What is this used for?
Decking, flooring, siding and trim.
Is a linear foot different from a regular foot?
No. A linear foot is 12 inches of length. The word linear only makes clear that you are measuring length and not area.
How many linear feet are in 100 square feet?
It depends on the width. Material 12 inches wide needs 100 linear feet, 6 inches wide needs 200, and 4 inches wide needs 300.
Can I convert square feet to linear feet without a width?
No. Square feet include width and linear feet do not, so the width of the material is the missing piece.
How do I convert linear feet back to square feet?
Multiply the linear feet by the width of the material in feet.