Roof Tile Calculator
Enter gross roof area, tile dimensions, and headlap to calculate total tile count including waste. Works for clay, concrete, and slate tile.
Get your exact tile count before ordering. Enter your gross roof area, tile dimensions, and headlap below to calculate the number of tiles needed.
Use the roof area calculator for accurate gross area.
Interlocking concrete tile: typically 13″. Clay barrel: 13–17″.
Physical length of the tile body before headlap deduction.
Vertical overlap deducted from tile length. Standard minimum: 3″.
Standard 10% for breakage and field cuts.
Enter tile dimensions
and roof area
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Roofing area, pitch, cost, and material estimation tools for residential and commercial projects.
Tile count formula
Tile roofing is calculated by exact piece count, not squares. The exposure area per tile — determined by subtracting the headlap from the tile length — is the core of the calculation. Using the gross tile dimensions instead of the exposed dimensions is the most common and costly ordering mistake.
Tile Exposure Area (Ea)
Ea = Tile Width × (Tile Length − Headlap)
Total Tiles Needed
Tiles = (Gross Roof Area ÷ Ea) × (1 + Waste%)
Worked example. Gross roof area = 2,000 sq ft, standard 16.5″ × 13″ interlocking concrete tile, 3″ headlap. Exposed length = 16.5 − 3 = 13.5″. Ea = 13.5 × 13 = 175.5 sq in = 1.218 sq ft. Net tiles = 2,000 ÷ 1.218 = 1,642. With 10% waste: order 1,806 tiles. To calculate the gross roof area needed here, use the roof area calculator.
Headlap explained
Headlap is the vertical portion of each tile that is permanently covered by the tile immediately above it. It is the primary waterproofing mechanism — water that penetrates past the visible surface hits the headlap of the tile below and drains back out. Reducing headlap below the manufacturer’s minimum (typically 3 inches) allows wind-driven rain to wick under the tile field.
| Tile type | Standard headlap | Min pitch |
|---|---|---|
| Interlocking concrete tile | 3″ | 4:12 |
| Clay barrel tile (mission) | 3″ | 5:12 |
| Natural slate (standard) | 3″ to 4″ | 4:12 |
| Natural slate (large format) | 4″ | 6:12 |
| Below-minimum pitch | Sealed underlayment required | — |
Tile weight and structural requirements
Tile roofing is heavy. Concrete tile weighs 900 to 1,200 lbs per square (9 to 12 lbs per sq ft). Natural slate runs 700 to 3,000 lbs per square depending on thickness. Standard asphalt shingles weigh only 200 to 350 lbs per square. Installing tile on a structure framed for asphalt shingles without structural engineering review can cause the roof to sag or fail. Always obtain a structural engineer’s sign-off before re-roofing with tile on an existing building. After calculating tile count, use the roof cost calculator to estimate total project cost including the higher labor rates that tile installation commands.
Frequently asked questions
What is headlap and why do I subtract it from the tile length?
Headlap is the vertical portion of a tile permanently covered by the tile installed immediately above it in the next course. Because this portion is never exposed to weather, it does not contribute to surface coverage. Only the exposed length — the visible portion below the overlapping tile — covers roof area. Using the full tile length overstates coverage by 15 to 25 percent depending on headlap size.
How do I calculate roof tile count for a hip roof?
Calculate the gross area of all roof planes using the roof area calculator, treating each plane separately if they have different dimensions. Sum the areas, then apply the tile exposure area formula to the total. Hip roofs require additional hip cap tiles — order approximately one hip cap tile per linear foot of hip run, plus 10 percent.
Do I need different tiles for the ridge and hip caps?
Yes. Ridge and hip cap tiles are purpose-made pieces with a specific profile that bridges the ridge board or hip rafter. They are ordered separately by the linear foot, not by the square. Typically one cap tile covers 10 to 12 linear inches along the ridge or hip. Never try to substitute field tiles for cap tiles — they will not shed water properly.
Can I install clay or concrete tile over existing asphalt shingles?
Only with explicit structural engineering clearance. The dead load of concrete tile (9 to 12 lbs per sq ft) is 4 to 5 times heavier than asphalt shingles. Standard residential framing is designed for 10 to 15 psf dead load — tile may double this. An engineer must review the rafter size, span, and spacing before installation.
What is the life expectancy of concrete tile versus clay tile?
High-quality clay tile properly installed lasts 50 to 100 years or more — some documented European tile roofs exceed 200 years. Concrete tile has a shorter expected lifespan of 40 to 60 years due to the gradual degradation of the cement matrix and color coating. Both are dramatically longer-lived than asphalt shingles but require higher structural investment upfront.
Why is tile installation so much more expensive than asphalt shingles?
Tile installation is slower per square than shingles. Each tile must be individually aligned, fastened with two nails minimum, and checked for alignment. Valleys require hand-cutting and flashing. Ridge and hip caps are mortared or mechanically fastened. A professional tile crew installs 2 to 4 squares per day versus 10 to 15 squares for asphalt shingles, driving labor cost 3 to 5 times higher.
What waste factor should I use for tile?
Use 10 percent for simple rectangular planes, 12 percent for standard hip roofs, and 15 percent for complex roofs with multiple valleys, dormers, and skylights. Natural slate requires 15 percent minimum due to inherent brittleness and the breakage rate during handling and cutting. Always order to the higher end — tile cannot be matched from another production batch after the project starts.
References
National Roofing Contractors Association. (2024). The NRCA Roofing Manual: Steep-slope Roof Systems. NRCA.
Boral Roofing. (2026). Concrete Roof Tile Installation Manual. Boral Building Products.
Tile Council of North America. (2023). Tile Installation Handbook. TCNA.