Clapboard & Bevel Siding Calculator

Clapboard and bevel are the classic tapered lap profiles behind the look of countless older homes. The single lever that controls your material is the exposure — the visible height of each course after overlap. A 4-inch exposure needs more boards than a 6-inch exposure for the same wall, even though the wall's square footage is identical. Fix the exposure and the count follows.

This calculator works in area and converts to squares, then to an approximate board count for your exposure. It suits wood clapboard and fiber-cement bevel alike; set the price to your material.

Coverage per board = board width minus overlap. Narrow the exposure and each board covers less wall, so board count rises while square footage stays put. That's why two houses of equal size can need different board counts.

The formulas are the same ones professionals use on paper: sum the walls, add the gables, subtract the openings, pad for waste, convert to squares. That part is exact. The variables are coverage and price, which shift by product and market — we seed them from manufacturer guidance and typical US installed costs and show ranges so you're not misled by a single number. Always confirm the coverage on your actual product's box and get a local quote before ordering.

Your result above answers the main question. Before you buy, run through the practical points that most affect a clapboard siding project, so the number translates cleanly into a real order.

• Confirm coverage: the default coverage is a planning figure. Check the exact coverage printed on your product's box or spec sheet and adjust it if it differs, since even a small change moves the piece count on a big wall.
• Match the waste to your walls: keep 10% for a simple rectangular house, and raise it toward 15% for gables, dormers, bay windows and lots of angled cuts, because those details generate short offcuts you can't reuse.
• Account for accessories: starter strip, trim, inside and outside corners, flashing and fasteners are all part of a complete order, not an afterthought — the takeoff above estimates each so your material list is whole.
• Keep a spare: hold back a piece or a full box for future repairs, since profiles and colors get discontinued over time and an exact match years later is hard to find.
• Time your order: have material delivered close to the start date, stored flat and dry, so it isn't sitting exposed or getting damaged before the crew arrives.

Re-run the numbers above after any change and lean on the per-wall audit to verify each surface one at a time, so what you order matches what the wall actually needs rather than a rough guess. That small habit is the difference between one clean delivery and a mid-project trip back to the supplier.