How do I calculate hip rafter length?

Hip length is derived from the roof span and pitch. For a standard hipped roof, each hip runs diagonally from eaves to ridge. The formula uses trigonometry: hip length = √(half-span² + half-span² + rise²).

How many hip tiles per metre?

Angular hip tiles typically run at 3 per metre, bonnet hip tiles at 3.3 per metre, and half-round at 2.8 per metre. Always add 10% for wastage and cuts.

What are hip irons used for?

Hip irons are galvanised steel brackets screwed to the hip rafter at regular intervals (typically 600mm). They mechanically support the hip tiles and prevent them sliding down the hip line.

Do I need bonnet tiles?

Bonnet hip tiles are a specific style that overlaps the main roof tiles at the hip junction. They give a traditional appearance and are commonly used with plain clay tiles. If you choose bonnet tiles, this calculator accounts for the higher tile count.

How much mortar do I need for hip tiles?

Allow approximately 1.5kg of mortar per hip tile for bedding and pointing. Use a 1:3 cement:sand mix. For a typical 4-hip roof with 5m hips, expect around 90-100kg of mortar.

TradeCalculator.co.uk

Hip Tile Calculator — Tiles, Irons & Mortar

Calculate hip tiles from roof pitch and span geometry. Includes hip irons, mortar requirements and bonnet tile counts.

Roof Span

Total span of the roof (wall to wall)

Roof Pitch

Typical UK pitch: 30\u201345\u00b0

Number of Hips

Standard hipped roof: 4 hips

Hip Tile TypeAffects tiles per metre

Price Per Hip Tile (optional)

How We Calculate This

This calculator computes hip rafter length from your roof span and pitch using trigonometry, then determines tile count based on the tile type.

The formula

Hip length = \u221a(half-span\u00b2 + half-span\u00b2 + rise\u00b2)

Hip tiles = Total hip run × Tiles per metre × 1.1 (wastage)

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.