Understanding your result
The headline is the field tiles to order, with breakage included. The stats give the pallets, the ridge and rake trim tiles and the installed weight. The breakdown shows the squares, the count per square for the tile you chose, the pallets, the trims and the dead load, plus the batten length for the gauge.
The two numbers to remember are the field tiles for the order and the dead load for the structure. The second one is not a detail: at 10 pounds per square foot the roof weighs as much as a car on every 300 square feet of it. The roof weight calculator sets it against the load of the roof it replaces, and the battens calculator counts the battens the tiles hang on.
If you are choosing between tile and slate, the slate calculator runs the same area and gives a comparable weight; synthetic slate and composite tile, at a fraction of the weight, are on the synthetic slate calculator.
How we calculate this
Tiles per square is the one figure that varies by product and pitch. The tile’s exposure (how much of it shows) is its length less the headlap, and the headlap is set by the maker for the pitch: 3 inches is typical for concrete tile at 4/12 and steeper. A tile 13 inches wide at a 13½-inch exposure covers about 1.2 square feet, which gives 85 to 90 per square. The maker’s data sheet prints the count for each headlap; enter it under “my product” if it differs from the default.
Weight is the installed figure, tile plus fasteners, from the same data sheets. The roofing material weights table lists it for every material on the site.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Tiles per square | 90 flat, 88 S-tile, 88 clay S, 160 two-piece barrel, 90 lightweight | Concrete and clay tile makers’ data sheets at standard headlap (Westlake Royal / Boral, Eagle, Ludowici) |
| Installed weight per square | 1,000 flat, 950 S, 900 clay S, 1,100 barrel, 600 lightweight (lb) | The same data sheets; standard concrete tile 900 to 1,100 lb |
| Tiles per pallet | 180 (360 barrel pieces) | Typical packaging; the supplier states the real figure |
| Ridge and rake tiles | 0.75 per foot | A 17-in trim tile lapped to about 16 in |
| Breakage and waste | 8% | Estimating practice: 5% plain gable, 10 to 15% with hips and valleys |
| Minimum pitch | 4/12 standard, 2½/12 with special underlayment | Manufacturers’ instructions referenced by IRC R905.3 |
Assumptions last reviewed October 7, 2026.
The calculator does not count the underlayment (often two layers or a self-adhering membrane under tile), the bird stop at the eaves, the hip and ridge nailers, or the mortar or foam adhesive some installations use. It does not decide whether the structure is adequate: that is an engineer’s call, and the guide on tile and slate weight explains what they look at.
Two worked examples
A gable roof in flat concrete tile
2,000 square feet (20 squares), flat concrete tile at 90 per square, 8% breakage, 40 feet of ridge, 72 feet of rakes.
- Field tiles: 20 × 90 × 1.08 = 1,944
- Pallets: 1,944 ÷ 180 = 10.8, so 11
- Ridge tiles: 40 × 0.75 × 1.05 = 32; rake tiles: 57
- Weight: 20 × 1,000 lb = 10 tons, 10 lb per square foot
Ten tons on the roof, against about 2½ tons of architectural shingles on the same 20 squares.
A hip roof in two-piece clay barrel
2,800 square feet (28 squares), two-piece barrel at 160 pieces per square, 12% breakage for the hips, 110 feet of ridge and hips, no rakes.
- Field pieces: 28 × 160 × 1.12 = 5,018
- Pallets: 5,018 ÷ 360 = 13.9, so 14
- Ridge and hip tiles: 110 × 0.75 × 1.05 = 87
- Weight: 28 × 1,100 lb = 15.4 tons, 11 lb per square foot
Five thousand pieces and fifteen tons: barrel tile is the heaviest and most labor-intensive common roof, and its four hips cost a sixth of the field tiles again in cuts and trims.
Where to find your inputs
Roof area. The sloped area from the roof area calculator, not the floor area.
Tile type and count. The maker and profile from the quote or the sample; the count per square and the weight from its data sheet, for your pitch.
Ridge, hip and rake lengths. Ridge from the plan; hips from the hip rafter calculator; rakes from the rafter length calculator or a tape on the rake board.
Common mistakes
- Ignoring the weight. Tile on a shingle structure is the most expensive mistake in this group. Check the load first.
- One count for every tile. Barrel tile counts pans and covers; flat tile is a single piece. Use the product’s own figure.
- No breakage. Tiles crack in delivery, in cutting and under feet. Eight percent is the floor, not the ceiling.
- Mixing batches. Colour varies between production runs. Order everything at once, and keep a few spares.
- Standard underlayment on a low pitch. Below 4/12 the maker wants a heavier underlay detail.
- Walking on the tile. Tile breaks under a boot in the wrong place. Repairs are a roofer’s job, walked on the lower third of each tile.
Questions people ask
- How many roof tiles per square?
- Most concrete flat and S-profile tiles cover a square with about 86 to 95 pieces at the maker's standard headlap, so the calculator uses 90 for flat and 88 for S-tile. Two-piece clay barrel tile is counted as pans and covers together, about 150 to 180 per square. A 20-square roof of flat concrete tile is 1,944 tiles with 8 percent breakage.
- How much does a tile roof weigh?
- Standard concrete tile installed weighs about 900 to 1,100 pounds per square (9 to 11 pounds per square foot), clay S-tile 800 to 1,000, two-piece barrel up to 1,100, and lightweight concrete 500 to 700. A 20-square roof of standard concrete tile is about 10 tons. Asphalt shingles are 230 to 430 pounds per square.
- Can I put tile on a roof built for shingles?
- Not without checking. Tile adds 6 to 8 pounds per square foot more than shingles, which rafters sized for a shingle roof may not carry, especially under snow. An engineer reviews the framing and specifies any reinforcement; lightweight concrete tile exists for exactly this situation. The roof weight calculator compares the loads.
- How many tiles are on a pallet?
- It depends on the tile's weight and the maker's packaging: roughly 150 to 200 flat or S-tiles, or 300 to 400 pieces of two-piece barrel. The calculator uses 180 and 360; the supplier states the real figure. Pallets are delivered by boom truck and loaded onto the roof in stacks of eight to ten tiles spread across the battens.
- What pitch does a tile roof need?
- Most concrete and clay tile is installed at 4/12 or steeper with a standard underlayment, and down to 2½/12 with a double or self-adhering underlayment and the maker's low-slope detail. Below that, tile is not a weatherproof roof. The International Residential Code (R905.3) refers to the manufacturer's instructions.
- How many ridge tiles do I need?
- Ridge and hip tiles are about 16 to 17 inches long and lap so each covers about 16 inches, which is 0.75 tiles per foot. Forty feet of ridge with 5 percent breakage is 32 ridge tiles. Rake (gable) tiles are counted the same way along each rake.