Roof Tiles Calculator

Calculate roof tiles, ridge tiles, batten and felt needed based on roof dimensions and pitch.

Last updated: April 2026 · Source: GOV.UK — Building Regulations Approved Document A

Tiles

1,343

Ridge Tiles

31

Batten

403m

Felt

135 m²

Roof Area

122.1 m²

Disclaimer

This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.

How It Works

The number of roof tiles depends on the roof area, tile type and pitch angle. Common UK roof tiles include concrete interlocking (approximately 10 tiles per m²), clay plain tiles (approximately 60 tiles per m²) and slate (approximately 20–30 per m² depending on size). The coverage rate accounts for the overlap (gauge) between rows.

Roof area is measured on the slope, not the floor plan. For a simple pitched roof, each side is calculated as: rafter length × eaves-to-eaves width. The rafter length depends on the pitch angle and the horizontal span. At 30°, the rafter is about 15% longer than the horizontal distance; at 45°, about 41% longer.

Enter the roof dimensions, pitch angle and tile type. The calculator shows total roof area (on slope), number of tiles, ridge tiles, hip tiles (if applicable) and estimated weight per m². Roof weight matters for structural calculations — concrete tiles weigh approximately 43 kg/m², while natural slate is about 30 kg/m².

Example: Simple gable roof, 8 m × 5 m plan, 35° pitch, concrete interlocking tiles

  1. Rafter length: 5 ÷ 2 ÷ cos(35°) = 3.05 m
  2. Each roof side: 8 × 3.05 = 24.4 m²
  3. Total roof area: 24.4 × 2 = 48.8 m²
  4. Tiles at 10/m²: 488 tiles + 5% waste = 513 tiles
  5. Ridge tiles: 8 m ÷ 0.33 m = 25 ridge tiles

Source: GOV.UK — Building Regulations Approved Document A

Frequently Asked Questions

What does the Roof Tiles Calculator do?
Calculate roof tiles, ridge tiles, batten and felt needed based on roof dimensions and pitch. All calculations are performed in your browser using official UK rates and thresholds.
Does this include waste allowance?
Yes. Most building material calculations include a standard 10% waste allowance. You can adjust this figure depending on the complexity of your project and cutting requirements.
Are prices accurate?
Material prices are indicative estimates based on average UK prices. Actual costs vary by region, supplier, brand and current market conditions. Always get quotes from local suppliers.