Roof tile calculator: tiles, ridge and battens
The calculator needs JavaScript. The worked example, formula and figures below show exactly how it works, so you can do the sum yourself. A guide, not advice. Check your supplier's or maker's figures before ordering.
Short answer
Worked example
| You enter | Value |
|---|---|
| Roof shape | Gable (two slopes) |
| Plan length | 10 m |
| Plan width | 5 m |
| I know the | Pitch |
| Roof pitch | 35 ° |
| Tile coverage | Tiles per m² (from the maker) |
| Tiles per m² at your gauge | 10 tiles/m² |
| Waste allowance | 5% |
Order: 641 roof tiles for 61.04 m² of roof
- Limit not yet confirmed Roof pitch against the tile's minimum pitch: 35 ° Enter the tile maker's minimum pitch for this tile to check it. UK-wide: Tile maker's minimum pitch (BS 5534). Check with the source.
| Result | Value |
|---|---|
| Tiles | 641 |
| Roof slope area | 61.04 m² |
| Plan area | 50 m² |
| Pitch | 35 ° |
| Tiles per m² | 10 tiles/m² |
| Rafter length (eaves to ridge, on the slope) | 3.05 m |
| Ridge | 10 m |
| Verges | 12.21 m |
| Eaves | 20 m |
Show the working
- Plan area: 10 × 5 = 50 m²
- Slope area: 50 m² ÷ cos(35°) = 50 ÷ 0.819 = 61.04 m²
- Rafter length: 2.5 m run ÷ 0.819 = 3.05 m
- Tiles: 61.04 m² × 10 per m² × 1.05 (5% waste) = 640.9, rounded up = 641
How it works
- Pitch from a rise: pitch = atan(rise ÷ run), where run = half the plan width (or the full width for a lean-to)
- Slope area = plan area ÷ cos(pitch) (the same for gable, hipped and lean-to roofs at one pitch)
- Tiles = slope area × tiles per m² × (1 + waste), rounded up
- From the tile size: gauge = tile length − headlap (single-lap) or (tile length − headlap) ÷ 2 (plain tiles); tiles per m² = 1 ÷ (gauge × cover width)
- Rafter length = run ÷ cos(pitch); hip length = √(2 × run² + rise²); ridge = plan length (gable) or plan length − plan width (hipped)
- Battens (m) = slope area ÷ gauge; verge units = verge length ÷ gauge, rounded up
Each tile has a minimum pitch and a headlap set by its maker for your exposure: check the maker's data and BS 5534.
Hipped roofs here have all four slopes at the same pitch and the ridge along the longer side.
Our default (adjustable)
These are typical planning figures and our own allowances, not facts about your product. Change any of them in the calculator to match your bag, pack or tin.
| Figure | Our default (adjustable) | Kind | Source |
|---|---|---|---|
| Waste allowance | 5 % | Our assumption Not yet checked against the source | Our choice: change it to suit your job brief v2 R1 (test RT1 uses 5%). Researcher to confirm against tile makers' guidance. |
Regulations and standards
- BS 5534 (slating and tiling): minimum pitch, headlap and fixings from the tile maker
Explained: BS 5534 (slating and tiling).
BS 5534 is used across the UK; each tile's minimum pitch comes from its maker.