Roof tile calculator
The number of tiles per square metre depends on the tile: large interlocking tiles need few, small plain tiles laid double need almost three times as many. Start from the actual roof area, not the footprint.
Your measurements
Result
- Area to order (incl. waste)
- 126.00 m²
- Tiles needed
- 1,638 pcs
Ridge tiles (2.5–3 per running metre), verge and ventilation tiles are counted separately.
How the calculation works
- Area to order = actual roof area + 5% waste (10% for roofs with many ridges, hips and valleys).
- Tiles = area to order × tiles per m²: ~13 for interlocking clay, ~10 for concrete or large-format, ~32 for plain (beaver-tail) tiles.
Worked example
For 120 m² of gable roof with 5% waste you order for 126 m². With interlocking clay tiles (~13 per m²) that is 126 × 13 = 1,638 tiles.
What the calculator assumes
- Tiles per m² are average values from manufacturers' data; the exact figure depends on the model and the batten gauge, and so on the pitch.
- Plain tiles are laid double-lapped, which is why they need almost three times as many pieces.
When to adjust the result
- Ridge tiles (2.5–3 per running metre), verge, ventilation tiles and fixings are not included.
- Underlay, counter-battens and battens are calculated separately.
- Metal roofing is sold in sheets by the length of the slope — for it the area counts, not pieces.
Ordering tiles and fittings
Take the exact tiles per m² from the data sheet for your batten gauge — it depends on the roof pitch. Count ridge tiles per metre of ridge and hip, verge tiles along the gables, and ventilation, snow-stop and pass-through tiles separately from the manufacturer's list.
Order the whole roof in one batch because clay colours vary between batches, and mix tiles from several pallets as you lay them. Check the pitch is above the minimum the manufacturer allows for the model; below it, extra underlay measures or another product are needed.
Frequently asked questions
How many roof tiles per square metre?
Around 10–15 for interlocking tiles, depending on the model, and around 30–35 for plain tiles. The manufacturer's data sheet gives the exact figure for your batten gauge.
How much spare tile should I keep?
Order 5–10% waste and keep a few spare tiles from the same batch for repairs.
How much spare should I order?
About 5% on simple gable roofs and up to 10% with many hips, valleys and dormers, plus a few spares for future repairs.
Can I mix tiles from different batches?
Mix them across the roof as you lay so colour differences blend, rather than finishing one slope with a different batch.