Square Feet to Linear Feet Calculator
Linear feet depend on the width of what covers the area. Enter the area and the actual face width of your boards to get linear feet, a waste allowance you control, and the number of full-length boards to buy.
Last updated:How the Conversion Works
Linear feet = square feet × 12 ÷ face width in inches. The result is the total edge-to-edge length of boards needed to cover the area, before any cutting.
Because the width drives everything, "sq ft to linear feet" has no single answer without it — our square feet vs linear feet guide explains when each unit is quoted.
Use the Width You Measured, Not the Name on the Pile
The single most common ordering mistake on this conversion is dividing by the name of the stock instead of the face width you can measure with a tape. Lumber and flooring are sold by nominal size and milled smaller:
| Sold as | Typical measured face width | Linear feet for 100 sq ft |
|---|---|---|
| Nominal 6 in decking | 5.5 in | 218 (not 200) |
| Nominal 3 in strip flooring | 2.5–3 in, varies by mill | 480 at 2.5 in, 400 at 3 in |
| Actual 6 in fence picket | 5.5 in on many pickets | 218 (not 200) |
Dividing by 6 when the board is 5.5 in wide asks 100 sq ft to be covered by 200 linear feet of board that can only cover 91.7 sq ft of it — about 9% short, before a single cross-cut. Measure three boards from the bundle you actually bought and use that number.
Leave the width field at the face width. If you deliberately want gaps — a deck you want to drain, a fence you want to see through — the gap does not consume board length; it opens up area the wood never covers. Then the area you need to buy wood for is the covered share, so the face width stays in the divisor.
Fences Have Three Different Divisors
Picket fences are where this conversion goes wrong most often, because "6 in picket" and "6 ft of fence" are not the same measurement:
- Solid stockade, pickets butted edge to edge: coverage per picket is its full face width, so use that width — 5.5 in pickets behind 100 sq ft of fence face need 218 linear feet.
- Spaced pickets (dog-trot or shadow-box look): each picket is centred one picket-width plus one gap apart, so the wood you need falls while the fence still spans the same area. For 5.5 in pickets at 1 in gaps the wood covers 5.5 ÷ 6.5 = 85% of the face, so 100 sq ft of fence line takes about 185 linear feet of picket, not 218.
- Board-on-board with overlap: each picket covers its width minus the overlap on both rails' sides. A 6 in picket with 1 in of overlap each side covers 4 in of face, so use 4 in as the width: 100 sq ft of face needs 300 linear feet.
Rails and posts are not this calculation at all — they are priced by the stick. Measure the run length for rails and add the number of post holes; do not run them through an area-to-length conversion.
From Linear Feet to a Buying List
Linear feet is a yardstick, not an order. Two more steps turn it into what you carry out of the yard:
- Add the cuts. Cross-cuts at walls and corners, the offcut at the start of each row that is too short to reuse, and boards you cull for knots or warp are where the waste comes from. 10% is the usual starting allowance for a straight lay in a square room; 15% for diagonal or herringbone layouts, or for a long run with many obstructions. Nothing fixes that number for your job — measure the room's perimeter and let the layout decide.
- Divide by the length you can actually buy. 264 linear feet in 8-foot boards is 33 boards. Mixed lengths in one order do not change the total length, but they do change how many partial boards you finish a row with, so buy the longest length your room's longest run allows.
Worked: 100 sq ft of 5.5 in decking is 218.2 net linear feet. At 10% that is 240 linear feet, which is 30 boards at 8 ft each.
Board feet, if the yard quotes that way. A board foot is a volume — 12 in × 12 in × 1 in, which is 144 cubic inches. Convert with linear feet × width in ÷ 12 × thickness in. 218.2 linear feet of 5.5 in stock at 1 in thick is 100 board feet; the same boards 2 in thick is 200 board feet.
Quick Reference (100 sq ft)
| Actual face width | Net linear feet | +10% waste | 8 ft boards |
|---|---|---|---|
| 2.5 in (trim, strip floor) | 480 ft | 528 ft | 66 boards |
| 3 in | 400 ft | 440 ft | 55 boards |
| 4 in | 300 ft | 330 ft | 42 boards |
| 5 in (plank) | 240 ft | 264 ft | 33 boards |
| 5.5 in (decking) | 218 ft | 240 ft | 30 boards |
| 6 in (picket, solid) | 200 ft | 220 ft | 28 boards |
| 8 in | 150 ft | 165 ft | 21 boards |
Board counts round up to whole boards, which is why they carry slightly more than the 10% waste already added.
FAQ
How do I convert square feet to linear feet?
Multiply the area by 12 and divide by the board face width in inches: 100 sq ft × 12 ÷ 5 in = 240 linear feet.
Why can't square feet convert to linear feet without a width?
Linear feet measure length along one edge. The same 100 sq ft can be one 100-ft strip that is 1 ft wide, or 240 ft of 5-inch plank — the width decides how much length covers the area.
Should I use the nominal name or the measured width?
The measured face width. A nominal 6-inch deck board is about 5.5 inches wide, so dividing by 6 gives 200 linear feet for 100 sq ft when the boards actually need 218 — roughly 9% short before any cutting waste.
How many linear feet of 5-inch flooring for a 12x12 room?
144 sq ft × 12 ÷ 5 = 345.6 linear feet. Add 10% for cuts: 380 linear feet, which is 48 boards if you buy 8-foot lengths.
Are linear feet the same as board feet?
No. A board foot is a volume — 12 in × 12 in × 1 in, or 144 cubic inches. Take linear feet × width in inches ÷ 12 for a 1-inch-thick board, then multiply by the thickness in inches. 218.2 linear feet of 5.5-inch, 1-inch stock is 100 board feet.
Sources and How to Check This Yourself
- The conversion itself is arithmetic: area ÷ width, with the 12 to move inches into feet. Nothing external is needed to verify 100 × 12 ÷ 5.5 = 218.2.
- Nominal-vs-actual face widths vary by mill and species, so they are stated here as "measure three boards from your own bundle" rather than as a published table. Bring a tape to the yard.
- Waste allowances of 10% straight-lay and 15% diagonal are ordinary estimating practice used to size an order. They are not fixed by any standard cited here — no flooring authority document was retrieved that states them, so treat them as starting points and adjust to your room's number of cuts.
- Board-foot definition (144 cubic inches) is the standard lumber volume measure; the arithmetic above is checkable in one line.