Siding Calculator

How to Calculate Siding for a House?

Add the lengths of all exterior walls for the total perimeter. Multiply by the wall height for gross wall area. Subtract the area of all doors (approximately 21 sq ft each) and windows (approximately 15 sq ft each). Add 10-15% waste. Divide by 100 to get siding squares. The calculator above estimates the number of siding boxes or cartons, starter strip, J-channel, corner posts, and other accessories needed for vinyl, wood, or metal siding based on your wall perimeter and height.

What Types of Siding Are Available?

Vinyl siding is the most popular residential choice at $3-$7 per square foot installed. It requires no painting, resists rot and insects, and comes in dozens of colors and profiles. Fiber cement (James Hardie) costs $5-$10 per square foot installed and offers superior fire resistance, impact resistance, and dimensional stability. It accepts paint and can replicate the look of wood, stone, or stucco. Wood siding (lap, board and batten, shingle) costs $6-$15 per square foot and provides a natural, traditional appearance that requires periodic painting or staining. Engineered wood (LP SmartSide) offers the look of wood with better moisture and insect resistance at $4-$9 per square foot.

What Accessories Does Siding Need?

Starter strip runs along the bottom of the first course to lock the first row of siding panels in place. Length equals the wall perimeter. J-channel (or J-trim) frames the edges around windows, doors, and where siding meets a different material. Measure the perimeter of each opening and add together. Corner posts cover the inside and outside corners of the building. Count the number of each corner type and buy posts that match the wall height. Utility trim (undersill trim) finishes the top course under eaves and soffits. F-channel or H-bar connects siding to the soffit. Each accessory piece typically comes in 12-foot lengths.

How Much Siding Comes in a Box?

Vinyl siding boxes typically contain 2 squares (200 sq ft) of siding, though this varies by profile and manufacturer. A box of standard double-4 vinyl siding contains about 24 pieces at 12 feet 6 inches long, covering 200 sq ft. A house with 1,500 sq ft of net siding area plus 15% waste needs about 1,725 sq ft, or 9 boxes of 200 sq ft each. Fiber cement planks are sold by the piece (usually 12 feet long at 5.25 or 8.25 inch exposure). Wood siding is sold by the linear foot or board foot. Always verify the coverage per unit with the specific product you choose before ordering.

How to Measure a House for Siding?

Measure each wall separately. For rectangular walls, multiply width by height. For gable ends, calculate the rectangular portion plus the triangular gable area (1/2 x base x gable height). Subtract every window and door opening. Measure the perimeter of each opening for J-channel. Count inside and outside corners. Note any areas where siding meets a different material (stone veneer, brick wainscot) for transition trim. A detailed measurement sheet wall by wall prevents ordering errors. Most siding contractors offer free estimates that include precise measurements if you prefer professional help with this step.

How Much Does Siding Cost?

Material and installation costs per square foot: Vinyl $3-$7. Fiber cement $5-$10. Engineered wood $4-$9. Natural wood lap $6-$12. Cedar shingle $8-$15. Metal $7-$15. Stone veneer $15-$35. Stucco $6-$10. An average 1,500 sq ft siding project costs $4,500-$10,500 for vinyl or $7,500-$15,000 for fiber cement, fully installed. Re-siding over existing siding (where code allows) saves the cost of tear-off and disposal ($1-$2 per sq ft). Labor typically represents 50-60% of the total siding project cost.

How Long Does Siding Last?

Vinyl: 20-40 years with no maintenance beyond occasional washing. Fiber cement: 30-50 years with repainting every 10-15 years. Engineered wood: 20-30 years with painting every 5-10 years. Natural wood lap: 20-40 years with regular painting or staining every 3-7 years. Cedar shingle: 30-50 years with periodic treatment. Brick veneer: 100+ years. Stone veneer: 50+ years. Stucco: 50-80 years over a proper lath system. These lifespans assume correct installation with a weather-resistant barrier, proper flashing, and adequate drainage behind the siding. Installation errors (missing house wrap, no kickout flashing, trapped moisture) cause premature failure regardless of material quality.

Siding Installation Best Practices

Install a weather-resistant barrier (house wrap like Tyvek) over the wall sheathing before any siding goes on. This barrier stops bulk water while allowing moisture vapor to escape from inside the wall cavity. Flash all window and door openings with self-adhering membrane integrated with the house wrap in a shingle-lap fashion (upper layers overlap lower layers). Leave a 1/4-inch gap at all trim and accessory contact points for thermal expansion (especially critical for vinyl). Nail siding loosely at center of nail slots so panels can move with temperature changes. Do not face-nail through the siding panel. These details prevent the most common siding failures: water infiltration and buckled panels from thermal expansion.

Frequently asked questions