How to Calculate Linear Feet in 2026: Fence & Baseboards

What is a linear foot?#

A linear foot—sometimes called a lineal foot—measures distance along a straight or curved path. One linear foot is the same length as one ordinary foot:

1 linear foot = 1 foot = 12 inches

The word linear clarifies that the measurement is one-dimensional. It does not include the material’s width, thickness or area.

An 8-foot board, an 8-foot pipe and an 8-foot strip of molding are each 8 linear feet long. Their cross sections may be completely different, but their measured lengths are equal.

This distinction prevents a common estimating mistake:

According to the National Institute of Standards and Technology, the international inch is exactly 25.4 millimeters. Therefore, one international foot is exactly 0.3048 meter. Those exact definitions are used for the conversions in this guide and the calculator.

Choose the calculation that matches what you know#

“How do I figure linear feet?” has several correct answers because projects begin with different measurements.

Do not force one method onto a different kind of project. A fence with irregular sides should be measured as separate runs, while a rectangular room can be calculated from its perimeter.

Calculate linear feet from equal pieces#

When every piece has the same length, multiply the number of pieces by the length of one piece:

Total linear feet = Number of pieces × Length of each piece

Example: ten 8-foot boards#

10 boards × 8 ft = 80 linear ft

The measured quantity is 80 linear feet. If the project also needs a waste allowance, apply it afterward rather than changing the meaning of the base measurement.

For example, with 10% extra:

80 linear ft × 1.10 = 88 linear ft to plan for

Waste is a purchasing assumption, not part of the linear-foot definition.

Add separate measured runs#

For walls, fences, trim and other layouts with different segments, add each run:

Total linear feet = Run 1 + Run 2 + Run 3 + …

If a repeated run appears more than once, multiply its length by its quantity before adding the other rows:

Total = Σ (Run quantity × Run length)

Example: mixed trim runs#

Suppose a project has:

• Two 12-foot runs
• One 9-foot run
• Three 4-foot runs

The total is:

(2 × 12) + (1 × 9) + (3 × 4)
= 24 + 9 + 12
= 45 linear ft

Labeling the runs during measurement makes the estimate easier to audit. If the total looks wrong later, you can compare each entry against the room or site rather than repeating the entire measurement.

How to calculate linear feet for a fence#

Walk the proposed fence line and measure every side that will receive fencing. Add those runs, then subtract gates or unfenced sections if they were included in the measurements.

For a simple rectangle:

Gross perimeter = 2 × (Length + Width)
Net fence length = Gross perimeter − Gates − Unfenced sections

Fence example: 60 × 40-foot yard#

Assume a rectangular fence line measures 60 feet by 40 feet and includes one 4-foot gate:

Gross perimeter = 2 × (60 + 40)
                = 200 ft

Net fence run = 200 − 4
              = 196 linear ft

The result is the net fence-line length. It does not yet determine the number of panels, posts, rails, pickets or concrete bags.

For example, dividing 196 feet by an 8-foot panel width gives 24.5 panel-width equivalents. Real panel placement must account for corners, terminal posts, gate posts, slopes and the manufacturer’s actual panel dimensions. Rounding 24.5 to 25 panels without checking the layout may still be wrong.

For an irregular property, measure the real runs separately. Do not use a rectangular perimeter unless the fence actually follows that rectangle.

How to calculate linear feet for baseboards#

Measure every wall section that receives baseboard and subtract doorways or other omitted sections.

For a rectangular 14 × 11-foot room with one 3-foot doorway:

Room perimeter = 2 × (14 + 11)
               = 50 ft

Net baseboard run = 50 − 3
                  = 47 linear ft

If baseboard is sold in 8-foot pieces:

47 ÷ 8 = 5.875

Six pieces provide 48 feet in total, but that arithmetic is not a cut plan. Miter cuts, scarf joints, damaged ends and the location of each seam can increase the order. A project with several short walls may reuse offcuts more efficiently than a project with long uninterrupted runs.

Record closets, bump-outs, cabinets, fireplaces and openings explicitly. Small missed returns can add up across several rooms.

Convert inches to linear feet#

Divide inches by 12:

Linear feet = Inches ÷ 12

Examples:

For feet and inches together, convert the inches to a fraction of a foot and add it:

8 ft 6 in = 8 + (6 ÷ 12)
          = 8.5 linear ft

To convert feet to inches, multiply by 12. To convert feet to meters, multiply by exactly 0.3048.

Can square feet be converted to linear feet?#

Yes—but only when you know the material’s installed coverage width.

Linear length = Area ÷ Installed coverage width

The area and width must use compatible units. If area is in square feet, convert width to feet before dividing.

Example: 120 square feet with 6-inch coverage#

First convert 6 inches to feet:

6 in ÷ 12 = 0.5 ft

Then divide the area by the coverage width:

120 ft² ÷ 0.5 ft = 240 linear ft

The reverse relationship is:

Area = Linear length × Installed coverage width

Two materials can cover the same area with different linear-foot totals. A product covering 4 inches per course needs more linear length than one covering 8 inches.

Use installed coverage width, not automatically the full product width. Lap siding, tongue-and-groove boards, overlapping roofing and similar products may lose part of their physical width to laps, joints or profiles. Follow the current manufacturer instructions for the exact product.

Linear feet of lumber versus board feet#

Linear feet measure lumber length. Board feet measure volume. A board foot equals 144 cubic inches, commonly visualized as a piece 1 inch thick, 12 inches wide and 12 inches long.

When thickness and width are in inches and length is in feet:

Board feet = Thickness × Width × Length ÷ 12

Rearrange the formula to find linear feet:

Linear feet = Board feet × 12 ÷ (Thickness × Width)

Example: 100 board feet at a 2 × 8-inch basis#

Linear feet = 100 × 12 ÷ (2 × 8)
            = 75 ft

That result depends entirely on the 2 × 8-inch basis. Using 1.5 × 7.25 inches instead produces a different length.

The USDA Forest Products Laboratory’s Wood Handbook includes a dedicated chapter on commercial lumber and provides broader technical context for lumber dimensions and wood products. For purchasing, verify whether the supplier’s board-foot tally uses nominal, rough-sawn or actual dressed dimensions. Do not mix dimension conventions inside one calculation.

How much waste should you add?#

There is no universal waste percentage for every linear material. The appropriate allowance depends on:

• Stock lengths available from the supplier
• Required segment lengths
• Whether offcuts can be reused
• Miter, scarf and lap joints
• Pattern or color matching
• Defects, breakage and site damage
• Minimum splice lengths
• Return policies and future repair stock

Keep the measured length and added allowance separate:

Planning length = Base linear length × (1 + Waste percentage ÷ 100)

Apply the allowance once to the combined base length. Do not add 10% to every row and then add another 10% to the total.

If material is sold only in whole pieces, calculate the required length after waste and then round up:

Whole pieces = Ceiling(Required length ÷ Stock-piece length)

The result is a basic order count. Check the cut schedule before buying expensive material.

Field-measurement checklist for 2026 projects#

Before finalizing an order:

1. Identify exactly which edges or runs receive the material.
2. Measure each run rather than relying only on a plan-scale estimate.
3. Record units beside every measurement.
4. Separate included runs from openings and exclusions.
5. Confirm installed coverage width when converting from area.
6. Confirm nominal versus actual dimensions for lumber.
7. Check available stock lengths and whether offcuts can be reused.
8. Add a visible, project-specific allowance only after calculating base length.
9. Recheck unusually large results with a second method.
10. Confirm quantities against the current drawings, product instructions or supplier takeoff.

For project pricing, continue to the cost per linear foot guide, which explains how to compare unit rates without mixing different scopes.

Common linear-foot mistakes#

Multiplying by width when only length is needed#

Length × width produces area. Use width only when converting between area and linear length or between board feet and linear feet.

Treating feet and linear feet as different sizes#

One measured foot equals one linear foot. “Linear” identifies the dimension being discussed.

Leaving inches mixed with feet#

Convert all values to one unit before adding or multiplying. Six inches is 0.5 foot—not 6 feet.

Subtracting an opening twice#

If individual runs already stop at a doorway or gate, do not subtract that opening again from the combined total.

Rounding every intermediate measurement#

Keep reasonable measurement precision through the calculation and round at the purchasing step. Repeated early rounding can accumulate error across many runs.

Assuming total stock length guarantees a workable cut layout#

The total can be sufficient while the available pieces are still too short for particular runs. Length arithmetic cannot replace cut planning.

Frequently asked questions#

How many feet are in one linear foot?#

One. A linear foot is one foot of length, equal to 12 inches.

Is 20 linear feet the same as 20 feet?#

Yes, when both describe length. “Linear feet” makes clear that the number is not square feet or cubic feet.

How do I find linear feet from length and width?#

If length and width describe a rectangle’s sides, use 2 × (length + width) to calculate perimeter. If width is a product’s installed coverage width and you know an area, divide area by width.

Does material width change its linear feet?#

Not when you directly measure its length. Width matters only when the task depends on area coverage or volume.

Can I calculate fence posts from linear feet alone?#

Not reliably. Post count also depends on spacing, corners, ends, gates, layout and product requirements.

Should I round linear feet up?#

Keep the base measurement as calculated. Round the purchasing quantity when material is sold in fixed lengths or increments, and show the extra separately.

Sources and methodology#

This guide uses dimensional analysis and exact published unit relationships. Worked project dimensions are illustrative; they are not recommended designs or universal waste allowances.

• NIST: SI Units — Length — exact international inch and metric relationship.
• NIST Special Publication 811 — SI usage and unit-conversion guidance.
• USDA Forest Products Laboratory: Wood Handbook (2021) — commercial lumber and wood-product reference context.

Reviewed September 10, 2026. Verify field dimensions, product coverage, stock sizes and project requirements before ordering.