HardiePlank & Fiber Cement Siding Calculator
Coverage tables for every Hardie profile, 12–15% waste built-in, cost ranges from $7–13 per square foot installed — with the James Hardie carton numbers baked in.
Siding inputs
Area: 360.00 sq ft
Area: 360.00 sq ft
Area: 270.00 sq ft
Area: 270.00 sq ft
Area (½ × base × height): 120.00 sq ft
Typical for Vinyl Double 4 (D4): ≈ $3.00/sq ft · edit above to override.
Final Estimate
Net Siding Area
1,244.00 sq ft
Order Area (with waste)
1,368.40 sq ft
Purchase This
Cost Breakdown
Planning estimate only. Confirm installed exposure, package coverage, supplier quantities, and local labor rates before ordering. Siding color batches change quarterly — buy 5–10% extra for matchability.
Area Breakdown
Trim & Accessories
150.00 linear ft of trim
14 pieces (itemized — each accessory rounded up separately)
Quick Hardie Estimator
Net area after openings. Add 12–15% waste for fiber cement.
Your Order Summary
Profile: HardiePlank Lap Siding (7.25″) · 130 sq ft/carton · waste 12–15%
James Hardie Fiber Cement Profile Comparison Matrix
Every fiber cement profile James Hardie currently produces — side-by-side with carton coverage, waste factor, and cost ranges. Benchmarked against published James Hardie specification sheets and field observations from siding installers.
| Profile | Exposure | Sq ft / carton | Waste | Material / sq ft | Installed / sq ft | Best for |
|---|---|---|---|---|---|---|
HardiePlank Lap Siding (7.25″)Winner | 7¼″ | 130 | 12–15% | $6–$9 | $8–$11 | Ranch homes, modern farmhouse, full-wall coverage |
HardiePlank Lap Siding (8.25″) | 8¼″ | 110 | 12–15% | $7–$10 | $8–$12 | Traditional lap look, fewer courses per wall |
HardiePlank Lap Siding (6″) | 6″ | 156 | 12–15% | $5–$8 | $7–$11 | Colonial style, more rows = more traditional look |
HardieShingle Siding | 10″ | 110 | 15–18% | $8–$13 | $9–$14 | Cottage accent walls, gable ends, decorative detail |
HardieBoard Panel Siding (12″) | 12″ | 120 | 10–12% | $4–$7 | $6–$9 | Modern horizontal panel, barn-style, economical |
All coverage numbers are benchmarked against official James Hardie carton labels from production runs 2024–2025. Regional distributors may carry older inventory with slightly different lot numbers — always verify the carton you will actually buy.
The 7.25″ and 8.25″ laps are separated by only $1–$2/sq ft installed but differ by 20 sq ft per carton. At 2,000 sq ft of wall area, that is 2 extra cartons and roughly $300–$500 more in material — not a “just aesthetics” choice.
Do not apply vinyl's 8–10% waste factor to Hardie siding — fiber cement's brittle edges chip when field-cut. A 10% waste estimate on Hardie will short you by roughly 2% on a typical house, and by 5–7% on houses with many openings.
James Hardie Carton Coverage: The Official Numbers
Unlike vinyl siding (which typically standardizes at 200 sq ft per carton across all Double-profile variants), James Hardie's carton coverage varies significantly by profile. These numbers come directly from the manufacturer's specification sheets — not estimates from a third party.
Why Hardie coverage differs
Fiber cement planks are heavier and denser than vinyl, which limits how many can ship safely in a single carton. Each carton is engineered for a specific exposure — the 6″ lap carton packs 30 planks because each plank's exposure is smaller, while the 8.25″ lap packs only 20 planks with a wider coverage area.
Carton label vs online numbers
James Hardie occasionally reformulates or repackages profiles between production runs. A 2023 carton of 7.25″ HardiePlank might say 132 sq ft while the 2025 carton says 130. Trust the label on the carton you will actually purchase — the numbers here reflect the most common current packaging.
Board count formula for any Hardie profile
Boards = Order Area ÷ (Exposure in inches ÷ 12 × Board Length in feet)Example: 2,260 sq ft order area at 7.25″ exposure, 12 ft boards → 2,260 ÷ (7.25÷12×12) → 2,260 ÷ 7.25 → 312 boards needed. Round up — partial boards do not ship, and you need extras for waste.
Hardie Siding Gable Calculator — How to Handle Triangular Walls
Gables are the triangular sections at the top of each end wall — and they are the single most commonly miscalculated part of any siding estimate. The formula is simple, but the inputs people use are usually wrong.
The correct Hardie gable formula
Gable Area = Base Width × Peak Height ÷ 2The base width is the width of the wall directly below the gable. The peak height is the vertical distance from the eave line (where the top of the wall meets the roof) up to the ridge of the roof — never the sloped rafter length you can see from the ground.
Don't use rafter length. A 24 ft wall with an 8 ft vertical peak gives 96 sq ft of gable — but measuring the sloped rafter instead of vertical height inflates this by roughly 15–25%.
Gable = triangle. Always use vertical peak, never sloped rafter.Photo: UnsplashHardiePlank Cost — A Deeper Dive
The $7–$13 per square foot installed range hides important distinctions that change your budget. Material, labor, tear-off, and trim all move independently.
Material (per sq ft)
$5–$9
Varies by profile & color
Labor (per sq ft)
$2–$4
Regional rate swing
Trim (per sq ft)
$0.80–$1.50
J-channel, corners, starter
Tear-off (per sq ft)
$1–$3
Old siding + disposal
Worked example — a 2,000 sq ft HardiePlank job
How to Use the Main Calculator for Hardie Siding
Select the Hardie profile preset
Open the main siding calculator, find the profile dropdown, and look for the Hardie preset. The default fiber cement profile carries our 7.25″ lap coverage of 130 sq ft per carton and a 13% waste factor.
Override with your carton number
If the carton you are buying says 128 sq ft instead of 130, type 128 into the carton coverage field. The calculator will instantly recalculate cartons, boards, and cost — making it trivial to compare James Hardie against a competitor's fiber cement carton.
Frequently Asked Hardie Siding Questions
How many square feet does a carton of HardiePlank cover?▼
It depends on the profile. 6″ lap covers 156 sq ft per carton, 7.25″ lap covers 130 sq ft, 8.25″ lap covers 110 sq ft, and HardieShingle covers 110 sq ft per carton. Always check the carton label — production runs can vary by 2–4 sq ft.
What waste factor should I use for Hardie siding?▼
Fiber cement requires 12–15% waste — higher than vinyl's 8–10% — because cement board chips easily when field-cut. Simple rectangular walls use 12%; houses with many gables and openings should budget 15%.
How much does HardiePlank cost installed?▼
Installed cost runs $7–$13 per square foot for standard lap profiles, with material at $5–$9/sq ft and labor at $2–$4/sq ft. HardieShingle pushes installed cost to $10–$18/sq ft due to the extra cutting involved.
Can I paint Hardie siding myself?▼
Yes — James Hardie recommends painting within 12 months of installation with a quality exterior latex paint. The factory priming is only a base coat; topcoat color is up to you. Expect to repaint every 10–15 years.
Does Hardie siding come in different colors?▼
HardiePlank is available in over 70 ColorPlus pre-finished colors — no painting needed, and backed by a 15-year labor-and-material finish warranty. Unprimed plank is cheaper but requires you to paint it after installation.
How do I calculate Hardie siding for a gable?▼
Gable area = base width × vertical peak height ÷ 2. Enter the dimensions into the calculator's gable section — just don't use sloped rafter length. Add 12–15% waste for the extra cutting around the triangular shape.
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