Linear Feet Calculator
This linear feet calculator converts square feet to linear feet, and linear feet back to square feet, for a material of a known width. It can also count the pieces of trim or boards you need from a total length, or work out the baseboard for a room from its perimeter minus the doors. Add a waste allowance, pick a stock length and read the steps.
Quick answer: linear feet = square feet × 12 ÷ width (in). 100 sq ft of 5.5 in boards is 218.18 linear feet, or 240 feet with a 10% waste allowance.
A linear foot is 12 inches of length. To turn an area into a length you need the width of the material: multiply the square feet by 12, then divide by the width in inches. To go the other way, multiply the length in feet by the width in inches and divide by 12. Pieces are the length with waste divided by the stock length, rounded up.
Example: 100 sq ft of boards 5.5 in wide is 100 × 12 ÷ 5.5 = 218.18 linear feet, or 240 feet with a 10% waste allowance. In 8 ft pieces that is 30 pieces.
Method
How this calculator works
The conversion is exact. What changes the answer is the width you use, whether gaps count and how much waste you add.
Square feet to linear feet and back
A board 1 ft long and w inches wide covers w ÷ 12 square feet, because 12 × w square inches is w ÷ 12 of the 144 square inches in a square foot. Flip that and one square foot needs 12 ÷ w linear feet. The conversion is exact, so the width is the only thing that changes the answer.
Linear ft = Sq ft × 12 ÷ Width (in)Sq ft = Linear ft × Width (in) ÷ 12Actual width, not nominal
Use the actual width of the material. A dry, surfaced 1×6, 2×6 or 5/4×6 deck board is 5-1/2 in wide, not 6 in. The actual sizes come from the American Softwood Lumber Standard (PS 20) as compiled by ArchToolbox, a secondary source. For trim, flooring and other products, use the width printed on the product.
Material width = actual width, plus the gap if boards sit apartWaste allowance
The default is 10% and you can set 0 to 50%. Retailer guidance puts waste for straight-lay flooring at about 7% to 10%, and a 10% allowance for waste and mistakes is a common recommendation for baseboard. They are conventions, not standards, so change the figure to fit your layout. A room with many corners needs more.
Length with waste = Linear ft × (1 + Waste ÷ 100)Pieces of stock and a room perimeter
Pieces are the length with waste divided by the stock length, rounded up. Stock lengths are 8, 10, 12 and 16 ft, or a custom length. For a room, the run is the perimeter minus the doorways, because baseboard stops at the casing. Counting from total length assumes offcuts can be reused, so the result is a lower bound for a tight job.
Room run = 2 × (Length + Width) − Doors × Opening widthPieces = Length with waste ÷ Stock length, rounded upLinear feet per 100 sq ft, by actual width
| Actual width | Common nominal sizes | Linear ft per 100 sq ft | Sq ft covered by 100 linear ft |
|---|---|---|---|
| 3-1/2 in | 1×4 | 342.86 | 29.17 |
| 5-1/2 in | 1×6, 2×6, 5/4×6 | 218.18 | 45.83 |
| 7-1/4 in | 1×8 | 165.52 | 60.42 |
| 9-1/4 in | 1×10 | 129.73 | 77.08 |
| 11-1/4 in | 1×12 | 106.67 | 93.75 |
What each field does
| Field | What to enter |
|---|---|
| What do you want? | Four views. Sq ft to linear ft (area ÷ width), Linear ft to sq ft (length × width), Pieces from a length (trim or boards) and Pieces for a room (perimeter minus doors). |
| Area to cover | Sq ft to linear ft only. The area of the surface, in ft² or m². |
| Material width | The two conversion views. Inches in the US view or millimeters in the metric view. Enter the actual width, not the nominal size: a 2 × 6 deck board is 5 1/2 in. Fractions work. If boards sit apart, enter the width plus the gap. |
| Total length | Linear ft to sq ft and Pieces from a length. The run of material, in feet or meters. |
| Material width (optional) | Pieces from a length and Pieces for a room. Leave it empty if you only need a count. If you fill it in, the result also shows the area the material covers. |
| Room length and Room width | Pieces for a room. The run starts from the perimeter, 2 × (length + width). |
| Door openings and Width of one opening | Pieces for a room. How many openings the baseboard does not cross, and how wide each one is. The defaults are 1 and 3 ft. |
| Stock length | The length of each piece you buy: 8, 10, 12 or 16 ft (2.44, 3.05, 3.66 or 4.88 m) or a custom length. |
| Custom stock length | Used when Stock length is set to Custom length. |
| Waste allowance | 0 to 50%, with 10% as the default. It covers cuts and defects. 7% to 10% is common for straight runs. |
Worked example: 100 sq ft of 5.5 in boards
Arithmetic checkedThe calculator's own example uses a 0% allowance and shows 218.18 linear feet, with 219 ft to buy after rounding up. The table uses the default 10%, which makes the length to buy 240 ft.
| Step | Math | Result |
|---|---|---|
| Linear feet | 100 × 12 ÷ 5.5 | 218.18 ft |
| In meters | 218.18 × 0.3048 | 66.50 m |
| With 10% waste | 218.18 × 1.10 | 240 ft |
| Pieces of 8 ft | 240 ÷ 8 | 30 pieces |
| Check back to area | 218.18 × 5.5 ÷ 12 | 100 sq ft |
| You would see | 218.18 ft (66.50 m), 240 ft with waste | |
Second example: baseboard for a 14 × 12 ft room
One 3 ft doorway, a 10% allowance and 8 ft pieces, in the Pieces for a room view.
| Step | Math | Result |
|---|---|---|
| Perimeter | 2 × (14 + 12) | 52 ft |
| Minus one 3 ft doorway | 52 − 3 | 49 ft |
| With 10% waste | 49 × 1.10 | 53.9 ft |
| Pieces of 8 ft | 53.9 ÷ 8 = 6.74, rounded up | 7 pieces |
| Left over after cutting | 7 × 8 − 53.9 | 2.1 ft |
| You would see | 7 pieces of 8 ft (56 ft in total) | |
Disclaimer
Results are planning estimates based on the dimensions and assumptions you enter. They are not engineering, structural or building-code advice. Product yields, densities and coverage vary by manufacturer, batch and site conditions. Check product labels, your supplier and your local building department before you order materials or start work. Read the full calculation disclaimer.
Accuracy
What affects your estimate
The formula is exact. What moves the answer is the width, the gaps, the waste and how your supplier sells the material.
Width is the number that matters
100 sq ft of boards that measure 5.5 in takes 218.18 linear feet. Using the name “6” instead gives 100 × 12 ÷ 6 = 200 ft, which is 18.18 ft or about 8% short. Measure the board or read the label.
Gaps change the count
For a 192 sq ft deck of 5.5 in boards, entering 5.5 gives 418.91 linear feet, and entering 5.5 + 0.25 in for the gap gives 400.70. Rows are whole boards, though: 144 in ÷ 5.75 in = 25.04, so 26 rows of 16 ft is 416 ft. The deck calculator counts rows, so order a deck from that.
Waste depends on the job
The default 10% suits a simple room or a straight run. Diagonal layouts and rooms with many corners need more, and 0% shows the exact length. The label on the product wins where it gives a figure.
Pieces assume offcuts are reused
Pieces come from the total length, so an offcut from one wall is assumed to fit another. Check the longest wall against the stock length and count wall by wall for a tight job. The “left over” line shows what the pieces leave.
Doorways and crown molding
Baseboard stops at a doorway, so Pieces for a room takes the door openings off. Crown molding runs over a doorway, so set the door openings to 0 for it. Sliding and wide cased openings count as openings too.
Freight linear feet
Carriers also say “linear feet” for the length of trailer floor a shipment takes. That is a shipping measure and does not follow the width formula, so this calculator does not cover it.
This calculator estimates quantities of material. Use the actual width and confirm how your supplier sells it: by the piece, by the linear foot or by the square foot. It quotes no prices and does not size framing, joists or decking structure.
Common mistakes
Converting square feet without a width
An area cannot become a length until you know how wide the material is. The same 100 sq ft is 218.18 ft of 5.5 in boards and 342.86 ft of 3.5 in boards.
Using the nominal size
A 1×6 or 2×6 is 5-1/2 in wide, not 6 in. The nominal name overstates the width, so the length comes out short.
Forgetting the gap
Decking and some siding sit apart. Add the gap to the width, then count whole rows, as the deck calculator does.
Not subtracting the doorways
Doorways have no baseboard. A 14 × 12 ft room with one 3 ft door needs a run of 49 ft, not 52 ft.
Rounding room by room
The room view works one room at a time. To pool several rooms, add their net lengths and enter the total in Pieces from a length, so you round up once. The baseboard guide shows a whole floor.
Questions people ask
How many feet equal a linear foot?
One. A linear foot is one foot of length, which is 12 inches, measured along a single line. “Linear” only says that width and thickness are ignored. “Lineal foot” means the same thing.
How is LF calculated?
For a run, add up the lengths in feet. For an area, multiply the square feet by 12 and divide by the width in inches: 100 sq ft of 5.5 in boards is 100 × 12 ÷ 5.5 = 218.18 LF. For baseboard, use the perimeter minus the doorways.
How do you convert linear feet to square feet?
Multiply the length by the width in inches, then divide by 12. For 200 ft of 5.5 in boards that is 200 × 5.5 ÷ 12 = 91.67 sq ft. When the material is 12 in wide, linear feet and square feet are the same number.
How to figure linear feet cost?
Multiply the length you need, with waste, by the supplier's price per linear foot. At a round $2.00 per linear foot, which is not a market price, 240 ft costs 240 × 2 = $480. If the supplier prices by the piece, multiply the pieces by the price per piece instead.
How many linear feet is a 10×10 deck?
A 10 × 10 ft deck is 100 sq ft. With 5.5 in boards and no gaps that is 100 × 12 ÷ 5.5 = 218.18 linear feet. With 1/4 in gaps each row takes 5.75 in, so 120 ÷ 5.75 = 20.87, which is 21 rows of 10 ft, or 210 ft. The deck calculator counts rows and boards.
Related calculators and guides
Sources
Where the numbers come from
- ArchToolbox, Lumber Dimensions (a secondary source) dry, surfaced actual widths citing PS 20, including 5-1/2 in for a 2×6 and 5/4×6, accessed October 16, 2026.
- Lumber Liquidators, Estimating your DIY flooring project (retailer guidance) straight-lay waste of about 7% to 10%, accessed October 16, 2026.
- This Old House, How to Install Baseboards measure each wall corner to corner and add an extra 10% for waste and mistakes, accessed October 16, 2026.
- Miniwebtool, Baseboard Trim Calculator (a secondary source) perimeter minus doorways, no door deduction for crown molding, common stock lengths of 8 to 16 ft, accessed October 16, 2026.
- Trex, Six tips for planning a successful deck build follow the manufacturer's gapping guidelines for board gaps, accessed October 16, 2026.
- NIST Handbook 44 (2026), Appendix C 1 foot = 12 inches = 0.3048 m exactly, behind the metric conversion, accessed October 16, 2026.