OneTripDIY

Linear Feet Calculator

Linear feet is just length, but the sum people actually need is how many boards of a given width it takes to cover an area — and that is what this does.

By The OneTripDIY Team · Updated

Measure the area to cover

Covering a run of trim or fence instead? Put the total run in Length and 1 in Width.

in

The face width you actually cover with. A 2x6 covers 5.5 in; tongue-and-groove covers less than its full width.

in

Decking usually leaves 1/8 to 1/4 in. Leave 0 for flooring and siding.

ft
%

10% covers cuts and the odd bad board.

in

Nominal thickness, for the board feet figure. 1 in for 1x, 1.5 in for 2x.

Buy this much —
Bare requirement — linear ft
Boards to buy — pieces
In board feet — bd ft
Area covered — sq ft

Estimates only. Check against your supplier's stated coverage before you buy.

Take this list to the store

We'll email the quantities above, what you typed in, and a link that reopens this calculator already filled in — so you can adjust it on your phone in the aisle.

We send the list you asked for. Anything else only if you tick the box, and you can unsubscribe in one click. What we do with it.

How to work it out

  1. Measure the area

    Length and width of the surface you are covering. For trim or fencing, put the total run in the length box and 1 in the width box — then the linear feet is simply that run.

  2. Use the covering width, not the name

    A 2x6 is 5.5 in wide, not 6. Tongue-and-groove flooring covers its face width only, which is usually a quarter inch less than the board. Using the nominal size is how people end up a box short.

  3. Set the gap

    Decking is laid with a 1/8 to 1/4 in gap for drainage, and that gap adds up: on a 16 ft wide deck it saves nearly three boards.

  4. Round to the lengths on sale

    Lumber comes in 2 ft steps. Buying the length that divides into your run with the least offcut is usually cheaper than buying the longest board available.

Linear feet per 100 square feet

How much board it takes to cover 100 sq ft, by covering width.

Board widthCoversLinear feet per 100 sq ft
1x4 (3.5 in)0.29 ft343 ft
1x6 (5.5 in)0.46 ft218 ft
1x8 (7.25 in)0.60 ft166 ft
2x6 decking (5.5 in + 1/4 gap)0.48 ft209 ft
5/4x6 decking (5.5 in + 1/8 gap)0.47 ft213 ft
1x10 (9.25 in)0.77 ft130 ft

What is a linear foot?

One foot of length, with the width ignored. Lumber, trim, fencing and gutter are all priced by the linear foot, so a 12 ft board is 12 linear feet whether it is a 1x4 or a 2x12.

That is why a price per linear foot cannot be compared between two different widths without doing this sum first.

Linear feet from square feet

Divide the area by the covering width in feet. A 5.5 in board covers 0.458 ft, so 192 sq ft of deck needs 192 ÷ 0.458 = 419 linear feet before waste.

Turning that into boards is a second step: 419 ft of 12 ft boards is 35 pieces, and the calculator rounds it for you after the waste allowance.

Linear feet and board feet are different

Board feet measure volume, not length: width in inches times thickness in inches times length in feet, divided by 12. Hardwood is sold that way; softwood dimensional lumber is sold by the piece or the linear foot.

Both figures are shown above, so you can price a job either way.

How this is worked out

No black box — here is the arithmetic the calculator runs, so you can check it against your own numbers.

  1. covering width = (board width + gap) ÷ 12 How much width one run of board actually covers, in feet.
  2. linear feet = area ÷ covering width Total length of board needed.
  3. × (1 + extra %) Cuts, offcuts and rejected boards.
  4. boards = linear feet ÷ board length, rounded up You buy pieces, not feet.
  5. board feet = linear feet × width × thickness ÷ 12 The volume measure hardwood is priced by.

Common questions

What is a linear foot?

Twelve inches of length, regardless of width or thickness. A 10 ft board is 10 linear feet.

How do I convert square feet to linear feet?

Divide the square feet by the width of the board in feet. For a 5.5 in board, that is dividing by 0.458.

Is a linear foot the same as a board foot?

No. A board foot is 144 cubic inches — 1 in thick, 12 in wide and 1 ft long. A linear foot is only length.

How many linear feet of decking do I need?

For 5/4x6 decking with a 1/8 in gap, about 213 linear feet per 100 sq ft. A 16 × 12 ft deck is 192 sq ft, so roughly 410 linear feet plus waste.

How much waste should I allow?

10% for straight runs, 15% if you are laying at 45 degrees or the deck is broken up by stairs and corners.

How do I work out linear feet for trim?

Measure each wall, add them up, and subtract door openings. Put that total in the length box with a width of 1 to get the same number back as linear feet.

Why is my board narrower than its name?

Because lumber is named by its rough sawn size and sold after planing. A 2x6 leaves the mill at 2 in by 6 in and reaches you at 1.5 in by 5.5 in.

Where these figures come from

Every figure below is traceable. How we check the numbers explains how they are verified, and the coverage reference collects them all in one place.

  • American Softwood Lumber Standard PS 20 — actual dressed sizes behind nominal lumber names
  • North American Deck and Railing Association guidance — gapping practice for decking boards
  • Hardwood retail practice — the board foot definition used for pricing

Think a number here is wrong? Tell us — we check every report, correct the page, and date the change. Last checked September 27, 2026.