RoofTally

Free calculator

Roof tile calculator (UK)

A 12 m by 9 m gable roof at 26.6° (6:12) has 120.7 m² of roof surface: 1,315 Marley Modern tiles at 9.9 per m² with 10% waste, 385 m of batten at the 345 mm gauge, and 27 ridge tiles. Pick the tile, type the plan size and pitch of each section, and add your price per tile for the cost.

Roof section

Marley gives the batten size (38 x 25 mm up to 450 mm rafter centres, 50 x 25 mm up to 600 mm); the fixing schedule (which tiles are nailed or clipped) comes from the fixing specification for your site.

Result

Roof area
124.6 m² (1,342 sq ft)
Tiles to order (10% waste)
1,358 tiles
Tiles on the roof, before waste
1,234 tiles at 9.9/m²
Battens (2.9 m per m² at 345 mm gauge)
398 m
Ridge tiles (12.2 m of ridge and hips)
27 ridge tiles
Tile cost (tiles to order x price per tile)
£2,105
Installed cost range, concrete tiles (supply and fit)
£9,971 to £18,696
Plan area (footprint with overhang)
111.5 m²

Tiles and battens are rounded up, waste included; ridge tiles are the ridge and hip length divided by the tile length, rounded up. The installed range is the published concrete tiles figure per m² (MyJobQuote, "Roof Tile Cost Guide", last updated 30 July 2026, cost per m² supplied and fitted, read 2026-09-20) times the roof area. Planning quantities from manufacturer coverage figures and published cost ranges, each with its source and date: measure the roof and follow the product data sheet. Not a structural assessment.

Ordering for the whole roof? Pro prints the materials list.

Every section with its area, the totals in bundles or tiles, underlayment, ridge, nails, drip edge, waste and the cost range, printable and as an Excel file.

See Pro

How it works

Roof area = plan area of each section (footprint plus overhang) x the pitch multiplier, the square root of 1 + (rise / run)². Tiles = roof area x the tiles per m² from the manufacturer data sheet x (1 + waste), rounded up. Battens = roof area x (1000 / gauge in mm) x (1 + waste), rounded up to the metre: one batten every gauge up the slope, so a 345 mm gauge takes 2.9 m of batten per m² and a 100 mm plain-tile gauge 10 m. Ridge tiles = the length of ridge and hips / the ridge tile length (457 mm for concrete, Marley, Ridge and Hip Tiles, read 2026-09-20), rounded up. Tile cost = tiles to order x your price per tile; the installed range = the published supply-and-fit figure per m² for the material x the roof area.

The same 12 x 9 m roof in plain clay tiles at 100 mm gauge takes 7,970 tiles and 1,329 m of batten, against 1,315 tiles and 385 m for Marley Modern: the coverage figure is what changes the order most, and it is read from each data sheet. Installed, the concrete tiles range of £80 to £150 per m² (MyJobQuote, "Roof Tile Cost Guide", last updated 30 July 2026, cost per m² supplied and fitted, read 2026-09-20) puts the Marley Modern roof at £9,660 to £18,112.

Coverage at the gauge used (Marley Modern (concrete interlocking) 9.9/m² at 345 mm gauge; Marley Mendip (concrete double pantile) 9.7/m² at 345 mm gauge; Marley Ludlow Plus (concrete interlocking) 15.7/m² at 312 mm gauge; Redland 49 (BMI, concrete interlocking) 17.7/m² at 282 mm gauge; Redland Grovebury (BMI, concrete interlocking) 9.7/m² at 343 mm gauge; Plain clay tile 265 x 165 mm (Marley Acme, 100 mm gauge) 60/m² at 100 mm gauge; Natural slate 500 x 250 mm (100 mm headlap) 20/m² at 200 mm gauge). Each manufacturer gives a higher figure at a 100 mm headlap for low pitches; type it in the tiles-per-m² field if your pitch needs it. Waste starts at 10% as a rule of thumb from the shingle trade, not a tile manufacturer figure. The fixing schedule (which tiles are nailed or clipped) depends on the wind zone and the pitch of your site and comes from the manufacturer fixing specification, not from this page.

Sources of the starting values

Frequently asked questions

How many roof tiles per square metre?
It depends on the tile and the gauge: Marley Modern (concrete interlocking) 9.9/m² at 345 mm gauge; Marley Mendip (concrete double pantile) 9.7/m² at 345 mm gauge; Marley Ludlow Plus (concrete interlocking) 15.7/m² at 312 mm gauge; Redland 49 (BMI, concrete interlocking) 17.7/m² at 282 mm gauge; Redland Grovebury (BMI, concrete interlocking) 9.7/m² at 343 mm gauge; Plain clay tile 265 x 165 mm (Marley Acme, 100 mm gauge) 60/m² at 100 mm gauge; Natural slate 500 x 250 mm (100 mm headlap) 20/m² at 200 mm gauge. Each figure is read from the manufacturer page or a merchant data sheet, with the date, and each is yours to change.
How much batten do I need per m²?
1000 divided by the gauge in mm: 2.9 m per m² at the 345 mm gauge of Marley Modern (Marley says "2.9 lin.m/m²"), 2.92 m at Grovebury's 343 mm (BMI: "2.92m/m2"), 10 m for plain tiles at 100 mm. The calculator adds the same waste as on the tiles and rounds up to the metre.
How many ridge tiles?
Ridge plus hips in metres, divided by the ridge tile length, rounded up: 457 mm for concrete ridges, 450 mm for clay (Marley, Ridge and Hip Tiles, read 2026-09-20). A hip roof adds four hips to the ridge; the calculator works them out from the plan size and the pitch.
Which waste figure should I use for tiles?
The calculator starts at 10% (Rule of thumb, not a tile manufacturer figure, read 2026-09-20), a rule of thumb rather than a tile manufacturer figure. Hips and valleys cut a lot of tiles, and cut halves can often be reused on the other side of a hip; type the figure your roofer uses, and keep the spares for repairs.
Where do the prices come from?
The price per tile is yours: two merchant listings were read on 2026-09-20 as starting values (Marley Modern, Grovebury) and the field is empty for the others, with typical ranges by material from MyJobQuote 2026 under it. The installed range per m² is MyJobQuote's supply-and-fit figure for concrete, clay or slate (MyJobQuote, "Roof Tile Cost Guide", last updated 30 July 2026, cost per m² supplied and fitted, read 2026-09-20); scaffolding and timber repairs are extra.
Does it work for slate?
Yes: natural slate 500 x 250 mm at 100 mm headlap is 20 per m² (Roofing Slate Direct, "Required Slate Quantity", read 2026-09-20) with a 200 mm gauge, (length minus headlap) / 2. For another slate size or headlap type the figure from the merchant coverage table.