StoreBox's Linear Feet Calculator
Lumber, trim, decking, fencing, fabric. Add up your pieces, convert an area into the linear feet you need, or flip square ⇄ linear — instantly.
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What is a linear foot?
A linear foot is just one foot of length, measured in a straight line — nothing more. It ignores width and it ignores thickness. A skinny strip of quarter-round trim and a wide 1×12 shelf board are both one linear foot when they're 12 inches long. The only number that matters is how far the material runs end to end.
That's exactly why so many building materials are priced "per linear foot" or "per foot": trim and moulding, baseboard, fencing, decking, dimensional lumber, pipe, gutter, countertop edging, and fabric off a bolt. You're buying a length, not an area. The confusion starts when people mix linear feet up with square feet (area) or board feet (volume) — so we'll clear that up below, and the calculator handles all three relationships for you.
Linear feet vs square feet vs board feet
These three terms get used interchangeably, but they measure completely different things. Getting them straight is the difference between ordering the right amount and being 12× over or short.
| Measure | What it counts | Formula | Used for |
|---|---|---|---|
| Linear feet | Length only (a straight run) | Just the length in feet | Trim, fencing, decking boards, fabric, pipe, gutter |
| Square feet | Area — length × width | Length ft × Width ft | Flooring, walls, tile, paint coverage, lawns |
| Board feet | Volume of lumber | (T in × W in × L ft) ÷ 12 | Hardwood, rough-sawn lumber sold by volume |
The quick test: if you can lay it out as a single line, it's linear feet. If it covers a surface, it's square feet. If you're buying thick hardwood where thickness changes the price, it's board feet. A 12 ft 2×6 is 12 linear feet, 6 board feet (2 × 6 × 12 ÷ 12), and covers about 5.5 sq ft of deck — three different numbers for the very same board.
How to calculate linear feet
There are two situations, and the calculator above has a tab for each.
From a list of pieces
Add the length of every piece, multiplying by how many of each you need:
This is the everyday case for trim, fencing rails, and cut lists. Use the "Add pieces" tab, enter each length with its quantity in whatever unit you measured, and it sums everything and converts to meters and yards.
From an area you need to cover
When you're covering a surface with boards or planks of a known width, divide the area by the board width in feet:
This is how you size decking, flooring, siding, paneling and shiplap. Narrower boards mean more linear feet to cover the same area — and more cuts and labor. The "Cover area" tab does this and estimates how many boards of your chosen length to buy.
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Linear feet for common projects
Fencing
Linear feet of fence is simply the perimeter you're enclosing — add up every side. A rectangular yard 40 ft × 60 ft needs 40 + 60 + 40 + 60 = 200 linear feet, no matter how tall the fence is. Subtract gate openings, then add posts every 6–8 ft.
Trim & baseboard
Measure the perimeter of each room at floor level and add it up, minus door openings. A 12 ft × 14 ft room is (12 + 14) × 2 = 52 linear feet, less ~3 ft per doorway. Add 10% for miter-cut waste.
Decking & flooring
Take the deck or floor area and divide by your board's coverage width. A 16 ft × 12 ft deck is 192 sq ft; with 5½-inch actual-width boards that's 192 ÷ 0.458 ≈ 419 linear feet. Round up to whole boards and add waste for the cuts at the ends.
Shelving
Just total the run of each shelf. Five shelves at 4 ft each is 20 linear feet of board, plus the vertical supports if they're cut from the same stock.
Fabric & sewing
Fabric off the bolt is sold by the linear yard or linear foot at a fixed bolt width. If a pattern calls for 6 linear feet (2 yards), that's the run length down the bolt — the bolt's 44 or 60-inch width is fixed. Use the "Add pieces" tab to total panels, then read linear yards from the results.
How to convert square feet to linear feet
You can only convert between square feet and linear feet if you know the width of the material — width is the bridge between a length and an area. The formulas:
Here's how a fixed 200 sq ft converts at different board widths — wider boards need fewer linear feet:
| Board width | Width in feet | Linear feet for 200 sq ft |
|---|---|---|
| 3 in | 0.25 | 800 lin ft |
| 4 in | 0.333 | 600 lin ft |
| 6 in | 0.5 | 400 lin ft |
| 8 in | 0.667 | 300 lin ft |
| 12 in | 1.0 | 200 lin ft |
Tips before you buy lumber
- Add 10% for waste. Miter cuts, end trimming and the odd warped board all eat into a length. Bump it to 15% for diagonal decking or patterned floors.
- Buy in standard lengths. Lumber comes in 8, 10, 12 and 16-foot pieces. Pick lengths that divide your runs cleanly to minimize offcuts — the calculator's board count assumes you can't use a piece shorter than one board.
- Nominal ≠ actual. A "1×6" is really 5½ in wide and a "2×4" is 1½×3½. Use the actual width in coverage and conversion math or you'll come up short.
- Account for gaps. Decking is usually spaced ⅛–¼ in apart. Those gaps slightly reduce the linear feet you need versus a gap-free calculation.
- Round up to whole boards. You can't buy 0.4 of a board. Convert linear feet into board count at your chosen length and round up every time.
Frequently asked questions
A linear foot is one foot of length measured in a straight line. It ignores width and thickness entirely — a 1-inch trim and a 12-inch board are both one linear foot if they're 12 inches long. Materials sold "per foot," like trim, fencing and fabric, are priced in linear feet.
Add up the length of every piece you need. Five boards 8 feet long is 5 × 8 = 40 linear feet. To cover an area instead, divide the square footage by the board width in feet: 120 sq ft of 6-inch boards is 120 ÷ 0.5 = 240 linear feet.
Linear feet measures length only, in a straight line. Square feet measures area — length times width. Trim, fencing and fabric are sold by the linear foot; flooring, walls and tile are measured in square feet. To move between them you need the material's width.
A 4 ft × 8 ft sheet is 32 square feet, and as a whole panel it is 8 linear feet long. If you rip it into strips, the linear feet depend on strip width: 6-inch strips give 32 ÷ 0.5 = 64 linear feet, and 4-inch strips give 96 linear feet.
Divide the square footage by the material width in feet. If the width is in inches, divide it by 12 first. Example: 200 sq ft of 8-inch decking is 200 ÷ (8 ÷ 12) = 200 ÷ 0.667 = 300 linear feet. The "Sq ⇄ Lin" tab does this both ways.
Linear feet is just length. Board feet is a volume measure for lumber: thickness (in) × width (in) × length (ft) ÷ 12. A 12 ft 2×6 is 12 linear feet but 6 board feet. Rough hardwood is usually sold by board foot; dimensional lumber and trim by linear foot.
Linear feet of fence is the total perimeter you're enclosing — add up every side of the run. A 40 ft by 60 ft rectangle is 40 + 60 + 40 + 60 = 200 linear feet, regardless of how tall the fence is. Subtract any gate openings from the total.
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Disclaimer: This tool is provided by StoreBox for informational purposes only. StoreBox makes no warranties regarding the accuracy of results and is not liable for any losses, damages, or costs arising from reliance on this calculator. Always verify quantities and costs with a qualified professional before placing orders or making purchasing decisions.