Hardie Board Siding Calculator
Whether it's lap or panel, get your Hardie board quantities and cost from a simple set of wall 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) |
|---|
Panels, planks and 'board'
'Hardie board' gets used loosely — sometimes it means the lap plank, sometimes the flat panel, sometimes the whole fiber-cement family. This calculator handles the area math the same way for all of them: measure the wall, remove the openings, add waste, convert to coverage. Pick the coverage that matches your product and you'll get an accurate board or panel count.
For panels (like a board-and-batten or vertical look), coverage per sheet is larger; for lap, it's per board. The tool reports squares either way so you can order confidently.
Step-by-step: from tape measure to order
The whole process is measure, subtract, pad, convert. Here's how that maps onto the fields above.
- Set your basics. Units and material at the top control everything downstream, so start there.
- Walls, one at a time. Enter width × height × quantity for each face of the house.
- Triangles and cut-outs. Add gable base and rise; subtract every significant window and door.
- Cushion and cost. Choose a waste percentage and, if you're budgeting, set labor and removal rates.
- Review the breakdown. Check the per-wall audit, then print or share.
Data sources and limitations
Two kinds of numbers feed this tool. The geometry — areas, openings, squares, waste — is fixed arithmetic and as accurate as your tape. The material coverage and the cost estimates are planning values based on common manufacturer specifications and reported US installed pricing; they vary with product line, region and labor, which is why they appear as ranges. Treat the result as a solid starting point for budgeting and ordering, subject to a field measure and your contractor's quote.
Getting the order right the first time
Your result above answers the main question. Before you buy, run through the practical points that most affect a hardie board 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.
Frequently asked questions
What is Hardie board?
How do I calculate Hardie board siding?
Is HardieBacker the same as Hardie siding?
How much does Hardie board add in weight?
Notes from the field
"Cleared up the 'board vs panel' confusion and gave me a real count."