How to Calculate Linear Feet
Part of Area & Volume
Quick answer
To measure linear feet, total the length of the material in a straight line — width and thickness don't matter. To convert an area to linear feet, divide the square footage by the piece width in feet: linear feet = ft² ÷ (width in inches ÷ 12).
There are two situations. If you already know the length, linear feet is just that length added up. If you only know the area to cover, you convert by dividing out the width of each board or plank.
The formula
Linear feet = Area in ft² ÷ (Piece width in inches ÷ 12)
Convert the piece width from inches to feet first (divide by 12), then divide the area by it. For 120 ft² of 5-inch-wide planks: 5 ÷ 12 = 0.417 ft, then 120 ÷ 0.417 = 288 linear feet.
Linear feet to cover 100 ft² by width
| Plank width | Width in feet | Linear feet per 100 ft² |
|---|---|---|
| 3.5 in | 0.29 ft | 343 lin ft |
| 5 in | 0.42 ft | 240 lin ft |
| 5.5 in | 0.46 ft | 218 lin ft |
| 7.25 in | 0.60 ft | 166 lin ft |
Add a waste allowance (about 10%) for cuts, defects and offcuts, then round up to whole boards. The linear feet calculator does the division, applies the waste and rounds for you.
FAQs
How do I calculate linear feet from inches?
Add up the lengths in inches and divide by 12. For example, three pieces of 30, 42 and 60 inches total 132 inches ÷ 12 = 11 linear feet.
How many linear feet do I need for flooring?
Divide the room's square footage by the plank width in feet. A 200 ft² room with 5-inch planks (0.417 ft) needs 200 ÷ 0.417 ≈ 480 linear feet, plus about 10% for waste.