Lap Siding Material Calculator

Calculate exact lap siding materials including boards, trim, corner pieces, and fasteners. Our calculator automatically adjusts exposure for even coursing and includes material-specific waste factors per IRC R703 and manufacturer specifications.

Lap Siding Calculator

Industry-standard calculations per IRC R703 & manufacturer specifications

Quick Answer

Most common: 8.25" fiber cement boards at 7" exposure = 15 boards per 100 sq ft. Add 10-15% waste. Calculate even coursing for wall height to avoid uneven top row.

Material Selection

Siding Material

Board Width

Board Length

Installer Level

DIY adds 5% waste

Wall Measurements

Wall 1

Width (feet)

Height (feet)

Wall Complexity

Gable end (triangular top)

Openings & Trim

Number of Windows

Avg Window Width (ft)

Avg Window Height (ft)

Number of Doors

Avg Door Width (ft)

Avg Door Height (ft)

Outside Corners

Inside Corners

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Want to Learn More?

Need calculations for all siding types including square footage only? Use our general siding calculator for vinyl, fiber cement, wood, and metal siding.

Read the Guide