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Fiber-Cement Siding Plank Reveal & Course Calculator

Calculate the number of fiber-cement lap siding courses needed for a wall, based on the plank's exposed reveal height.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax
9.84 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Siding courses needed

17 courses

High confidence

Running these inputs gives 17 as the siding courses needed. Currently reading for United States under IRC 2024 — pick a different market above and the figures re-cast accordingly.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Course count = ceil(wall height ÷ plank reveal), where reveal is the exposed (non-overlapped) height of each installed course — a standard fiber-cement plank has a fixed board width, but only the reveal portion shows once overlapped by the course above

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Why is the reveal not the same as the plank's full width?
Each course of lap siding overlaps the one below it, so only the exposed portion — the reveal — is visible on the finished wall. The reveal is always smaller than the plank's full board width.
Why does the course count round up?
A partial course at the top of the wall still requires a full course of material and installation labor, so the result is rounded up to the next whole course.
Does this account for the starter strip or trim at the top and bottom?
No — this calculates the number of siding courses based on reveal height alone. Starter strip, frieze board, and any trim details at the top or bottom of the wall should be planned separately.