Fiber Cement Siding Calculator
Works for any fiber cement brand — James Hardie, Allura, CertainTeed and more. Get boards, squares, boxes and cost from your measurements.
Walls (feet)
Gables / triangles optional
Windows & doors to subtract
Tip: measure each wall's width × height at its widest points. A per-wall audit table appears below so you can check every number.
Your siding squares, panels and cost appear here.
Estimated from wall count and perimeter — confirm against your actual corners and openings.
Cost per sq ft: – · per square: –
| Surface | Area (sq ft) |
|---|
One method, every fiber cement brand
Fiber cement lap all shares the same estimating logic regardless of who makes it: coverage per board is set by the plank length and the reveal, and your board count is net wall area over that coverage, plus waste. Whether you're pricing Hardie, Allura, Nichiha or a house brand, this calculator gives you a consistent number you can shop around.
Set the coverage-driving price to match your product, add your gables, subtract your openings, and read boards, squares and boxes. The cost band helps you compare fiber cement against vinyl or wood on your specific house.
Using the tool in five quick moves
You don't need to prep anything special — a tape measure and two minutes will do. Work through it in this order and the estimate builds itself.
- Pick the material first. That decides the default coverage, so it's the natural place to start before you type any numbers.
- Log every wall separately. Resist the urge to average; different heights and widths each deserve their own line.
- Handle the shapes above and the holes within. Triangular gables go in as base and rise; windows and doors come out as size and count.
- Dial in waste and pricing. Keep 10% unless the elevation is busy, then nudge it up. Drop in a real per-foot price when you have one.
- Take the numbers with you. Print or copy the breakdown and it's ready for the supplier's desk.
Brand-agnostic board count
The formula doesn't care about the label: coverage area ÷ coverage per board = boards. Only the coverage-per-board figure changes between products, so match it to your spec sheet and the count is accurate for any brand.
Where these numbers come from
The measuring method follows standard exterior-takeoff practice: gross wall area minus openings, converted to squares at 100 sq ft each, with a waste factor for offcuts. Coverage and waste ranges reflect published manufacturer installation guidance from makers such as James Hardie and vinyl producers, and cost ranges reflect commonly reported US installed prices. Local prices, product lines and codes vary, so treat the output as a well-grounded planning estimate — a field measure and your contractor's quote govern the final order.
Choosing between fiber cement brands
The board math is the same for every fiber cement maker, so the real decision is which brand fits your color, warranty and budget goals. Here's how they tend to differ.
- James Hardie: the category leader, widest color and trim program, strong warranty, premium price.
- Allura: competitive pricing, solid profiles, a common value alternative to Hardie.
- CertainTeed: known for color systems and a strong warranty on select lines.
- Nichiha / others: architectural panel looks and specialty textures for accent walls.
Because coverage is nearly identical, price the same board count across two or three brands using the cost inputs and let the number decide.
Frequently asked questions
How do I calculate fiber cement siding?
Which fiber cement brands does this work for?
Is fiber cement measured in squares?
How much does fiber cement weigh?
What waste factor for fiber cement?
What users tell us
"Priced three brands from one board count. The tool made comparison shopping easy."