Linear Feet Calculator for Siding
Siding is measured by the square (100 sq ft of coverage), but every job starts with calculating linear feet. Each material and profile has a different exposure — the amount of each course that remains visible after the overlap. Use this calculator to estimate the linear feet of siding panels you need, including adjustments for windows and doors.
Linear Feet for Siding
Calculate linear feet for siding
Sum of all exterior wall surfaces
Subtract at 50% net (half the actual opening area)
How Lap Siding Exposure Works
Lap siding (horizontal siding) works by overlapping each course over the one below it. The "exposure" is the visible portion of each course — typically half the total height. For example, a "Double 4-inch" vinyl panel has two 4-inch laps per 8-inch-total-height panel, with the bottom 4 inches of each lap visible. The 4 inches hidden behind the next course is called the overlap. Getting the exposure right is critical to linear-foot calculations: the larger the exposure, the fewer courses you need, and the less linear footage per square foot of wall.
Fiber cement siding (HardiePlank) typically uses a 7-inch exposure for the 8.25-inch-wide plank. Engineered wood products like LP SmartSide use an 8.25-inch exposure on a wider piece. Cedar lap siding uses a 6-inch or 8-inch exposure depending on the grade and style. The key formula is: Linear Feet = Wall Area (sq ft) ÷ (Exposure in feet), plus waste. For vinyl double-4 with 4-inch (0.333-foot) exposure, a 2,000 sq ft wall area requires roughly 6,000 linear feet of siding panel, before waste and opening deductions.
Siding Material & Panel Comparison
| Material | Std. Panel Length | Typical Exposure | LF per Square | Cost/LF (Installed) |
|---|---|---|---|---|
| Vinyl (Double 4) | 12 ft | 4" | 300 | $1.80 – $3.50 |
| Vinyl (Double 5) | 12 ft | 5" | 240 | $2.00 – $4.00 |
| Fiber Cement (Hardie) | 12 ft / 16 ft | 7" | 172 | $3.50 – $6.50 |
| Engineered Wood (LP) | 16 ft | 8.25" | 146 | $3.00 – $5.50 |
| Cedar Lap | 16 ft | 6" | 200 | $5.00 – $9.00 |
Prices are national averages including installation, 2026. One square = 100 sq ft of coverage. LF per square varies by exposure: LF = 100 ÷ (exposure in feet).
How to Calculate Linear Feet for Siding: Step-by-Step
- Measure each wall. Multiply height by width for each exterior wall. A standard 8-foot wall, 30 feet long, is 240 sq ft. Add all walls together for total gross wall area.
- Subtract for openings. Measure each window and door. Subtract roughly 50% of the total opening area — the remainder accounts for the cuts and material lost around each opening. For example, 300 sq ft of openings means you subtract 150 sq ft.
- Choose your exposure. Select your siding profile (double-4, double-5, etc.) and note the exposure. Convert to feet: 4-inch exposure = 0.333 ft.
- Divide to get linear feet. Take your adjusted wall area and divide by the exposure in feet. For 1,850 sq ft with 4-inch exposure: 1,850 ÷ 0.333 = 5,555 linear feet.
- Add the waste factor. Multiply by 1.10 (10% waste) or 1.12 (12%) to cover cuts, gable ends, and mistakes. 5,555 x 1.10 = 6,111 linear feet.
- Account for accessories separately. Starter strips, corner posts, J-channel, and soffit are measured separately in linear feet. A typical house needs 1 starter strip per linear foot of wall base, and 4 corner posts (each 9-10 feet) for a standard single-story home.
Siding Accessories Measured in Linear Feet
Beyond the siding panels themselves, several trim components are also measured in linear feet and must be budgeted for separately. Starter strips run the full perimeter of the house at the base of the siding, providing a clip for the first course. Corner posts cover the vertical joints at outside corners — standard posts are 9 to 10 feet long. J-channel frames windows, doors, and the soffit transition. Undersill trim locks the top course of siding at soffits and windows. Frieze board (belly band) separates stories on multi-level homes. Each of these accessories adds linear footage that should be tracked separately from the siding panels.