Ridge Tile Calculator: How Many Ridge and Hip Tiles?
By the Professional Roofers team
Updated 2026 · Independent cost guide
The number of ridge tiles you need depends on how much ridge each one actually covers, not on its length alone. A mortar-bedded tile covers its own length plus the joint; a dry ridge unit covers its length minus the overlap the system specifies. Enter your ridge and any hips below for a count of ridge and hip tiles, spares, mechanical fixings and end pieces.
Your ridge, hips and tiles
Do not know the hip length? Work it out from the ground
For a hip between two slopes of the same pitch, the hip length is the square root of (slope length squared plus half the roof span squared). Slope length is eaves to ridge measured up the roof; the span is the full width of the building the slope covers, front to back.
How the count works
Each tile's cover is the length of ridge it accounts for. On a mortar-bedded ridge the tiles are butted with a joint, so a 450 mm tile with a 10 mm joint covers 460 mm. On a dry ridge the units overlap or sit on a union piece, so the cover is the tile length minus that overlap, and the overlap varies between systems. The calculator divides each run by the cover, rounds up to whole tiles on every run separately (you cannot carry a part tile from one hip to the next), then adds spares.
Hips need their own count because each one is a separate run that starts at the eaves. A plain gable roof has one ridge and no hips; a fully hipped roof has a shorter ridge and four hips; a pyramid roof has no ridge at all and four hips meeting at a point.
Fixings and the pieces people forget
- Mechanical fixings. Since March 2015, BS 5534 has required ridge and hip tiles to be mechanically fixed, whether they are bedded in mortar or laid dry. Mortar alone is no longer enough. We count one fixing per tile; follow the manufacturer's kit, as some need more. Our dry ridge vs mortar ridge guide explains the rule.
- Gable ends. Where the ridge stops at a gable, the open end is either filled with mortar and slips or closed with a block-end or end-cap piece. The calculator lists one per open end.
- Junctions. Where hips meet the ridge you need a junction piece or a mitred, cut joint: typically a three-way piece where two hips meet the ridge end, or a four-way piece at the top of a pyramid roof.
- Hip irons. Mortar-bedded hips traditionally have a galvanised hip iron screwed to the hip rafter at the foot of each hip to stop the bottom tile sliding. Many dry hip systems use their own hip starter piece instead.
Ridge tiles are usually priced and sold individually, so ordering a couple of extras costs little next to a second delivery. If you are pricing a repair rather than a full replacement, see ridge tile repair costs; for the main slopes, use the roof tile calculator and the roof batten calculator.
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