SettingsSettings for this calculationUS
Waste is set to 5% by hand. Pick a tier above to replace it, or keep your own figure.
Every slope to be tiled, measured up the slope rather than on plan.
Length along the eaves times the rafter length from eaves to ridge, for each slope, added together; the triangles of a hipped end count at half their base times their slope height. A plan area is too small by the pitch: a roof at 35° covers about 22% more than its footprint. Leave out roof windows and anything else that takes the place of tiles.
Tools needed: Tape measure, The roof drawings, or a measurement from the ground
Each choice brings its maker's gauge, cover width and ridge tile at the minimum headlap; the last takes your own.
The Marley tiles carry the figures in each tile's technical specification, at the minimum headlap for the pitches it lists: 75 mm (2.95 in) for the interlocking tiles at 22.5° and above, 65 mm (2.56 in) for plain tiles. A lower pitch, a long rafter or an exposed site can call for more lap, which shortens the gauge and adds tiles: Marley's sheets give 100 mm (3.94 in) of headlap for its interlocking tiles below 22.5°, for example 10.7 Modern tiles a square metre (0.99 a square foot) rather than 9.9 (0.92). For that, or for any other tile or a natural slate, choose the last option and enter the length, cover width and headlap from the maker's specification for your roof.
The length of every ridge on the roof, added together.
A gable roof has one ridge the length of the roof; a hipped roof's ridge is shorter by the hips at each end. The ridge also sets the top courses: a plain-tile roof has a course of top tiles along both sides of it.
The length of every hip, measured along the hip from eaves to ridge, added together; 0 for a gable roof.
Hips are covered with the same maker's ridge and hip tiles as the ridge and counted at the same length each. A bonnet hip on a plain-tile roof is laid course by course instead and is counted from the maker's own figures.
The length of every eaves, added together; a plain-tile or slate roof needs a course of eaves tiles along it.
On a gable roof it is twice the ridge length; a hipped roof has eaves on all four sides. An interlocking tile needs no eaves course, so this only counts for plain tiles and slates.
The length of every verge, the sloping gable edges, measured up the slope and added together.
A gable roof has four, two at each gable, each the rafter length; a hipped roof has none. On a plain-tile or slate roof every second course needs a tile-and-a-half or slate-and-a-half at each verge.
How far each slope runs from the eaves to the ridge, measured on the slope; it sets the batten courses.
The battens are counted course by course up this length: the rafter over the gauge, rounded up, plus one for the eaves batten, as the site's Roof Batten Spacing Calculator counts rows. On a gable roof it is the verge length of one slope; the opening roof's 4 m (13.1 ft) rafters over a 10 m (32.8 ft) ridge make its 80 m² (861 sq ft).
How many separate slopes the roof has: 2 for a gable, 4 for a hipped roof on a rectangle.
Each slope has its own batten courses, cut to its own width, so the batten lengths are counted slope by slope; the width of a slope is the roof area over the slopes and the rafter length.
The length battens are bought in: Marley says 3.6 m (11.8 ft) or more is typical.
Marley supplies its BS 5534 battens in lengths of at least 3 m (9.8 ft), typically 3.6 m (11.8 ft) or more, and asks for every fixed length to be at least 1.2 m (3.9 ft) and to span three rafters. Joints land on a rafter, so a stock length that does not suit the rafter centres leaves an offcut at every join.
Extra tiles for the cuts at hips, valleys and verges, and for breakages. The page opens at 5%.
No maker cited here publishes a cutting allowance: their coverage figures are the tiles a square metre and nothing more, and Marley's own guide to roof tile sizes works 100 m² of its Acme plain tile as 100 × 60 = 6,000 tiles, adding nothing. So the allowance is yours. The page opens at 5%, the tightest of the site's own three crew-waste tiers, the one it gives a licensed contractor, and not a roofing figure; its other tiers are 10% and 15%. Raise it for hips, valleys, dormers and roof windows, where every course ends in a cut and clay in particular breaks; set it to 0 to see the count at the maker's coverage alone.
Roof tiles or slates
833 tiles
Marley Modern is counted at its 345 mm (13.6 in) maximum gauge, 420 mm (16.5 in) less its 75 mm (2.95 in) minimum headlap, and its 292 mm (11.5 in) cover width, as its specification gives them, and Marley's concrete ridge and hip tiles, 457 mm (18 in) long. The tiles are the slope area times the covering capacity, with the cutting allowance on top. The battens are counted course by course, the rafter over the gauge plus the eaves batten on every slope, each course in whole stock lengths.
- Batten gauge
- 13.58 in
- Covering capacity
- 0.92 tiles/ft²
- Tiles for the roof area, before cutting
- 794 tiles
- Cutting allowance
- 5 %
- Battens at the maker's coverage, area over gauge
- 759.79 ft
- Batten courses on each slope
- 13 courses
- Battens, total run
- 860 ft
- Battens in stock lengths, cut course by course
- 78 lengths
- Ridge tiles
- 23 tiles
- Hip tiles
- 0 tiles
- Eaves and top-course tiles or slates
- 0 tiles
- Tile-and-a-half or slate-and-a-half at verges
- 0 tiles
They open the calculator with your figures already in it
Roof Tile and Slate Calculator (Gauge, Battens and Ridge Tiles): 833 tiles — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Marley, Modern interlocking tile technical specification: 420 × 330 mm; minimum headlap 75 mm (22.5° and above); maximum gauge 345 mm; cover width 292 mm (nominal); covering capacity 9.9 tiles/m² at 75 mm headlap and 10.7 at 100 mm; battens required 2.9 lin.m/m² at 75 mm headlap and 3.1 at 100 mm; 38 × 25 mm battens to 450 mm rafter centres, 50 × 25 mm to 600 mm
- Marley technical specifications for Ludlow Major (420 × 330 mm, maximum gauge 345 mm, cover width 295 mm, 9.8 tiles/m² at 75 mm headlap), Edgemere (420 × 330 mm, 345 mm, 298 mm, 9.7 slates/m²) and Ludlow Plus (387 × 230 mm, maximum gauge 312 mm, cover width 204 mm, 15.7 tiles/m², 3.2 lin.m of batten/m²)
- Marley plain tile technical specifications: concrete plain tile 267 × 168 mm and Hawkins clay plain tile 265 × 165 mm; minimum headlap 65 mm on a roof; maximum gauge 100 mm on a roof; 60 tiles/m² and 10.0 lin.m of batten/m² at 100 mm gauge
- Marley (Kevin Taylor, Training and Technical Support Manager), setting out tiling battens: the maximum gauge is the full length of the tile less the minimum headlap (420 − 75 = 345 mm), never to be exceeded and usually eased so the gauge is even; marked up from the eaves course datum to the top batten under the ridge; plain tiles need an under-eaves batten, and room at the ridge for the top course, an additional batten and an eaves/tops tile; battens to BS 5534 are supplied in lengths of at least 3 m, typically 3.6 m or more, at least 1.2 m long and over three rafters when fixed
- Marley (Kevin Taylor), roof tile sizes, how many roof tiles per square metre: for a rough estimate multiply the size of the roof in square metres by the roof covering capacity, for example 100 m² of Marley Acme plain tiles at 60 a square metre, 100 × 60 = 6,000 tiles, with nothing added; a different gauge or headlap changes the figure
- Marley concrete plain eaves/top tile and tile-and-a-half: eaves have a double course throughout their length using purpose-made eaves tiles for the undercourse; the tile-and-a-half is required to achieve the broken bond laying pattern
- Marley ridge and hip tiles: angled hip and ridge tiles typically 245 or 260 mm across, in lengths of 450 mm for clay and 457 mm for concrete
- Bristile Roofing, Concrete Roof Tiles Technical Manual, Classic product specification: 440 × 335 × 35 mm; set-out 360 mm maximum; 9.26 tiles per m²; 2.5 ridges per lineal metre; 2.9 m of batten per m²; ridge capping is a tile used for both the ridge and hips; overlapping ridge tiles laid away from the prevailing wind; installation to AS 2050
- BS 5534:2014+A2:2018, Slating and tiling for pitched roofs and vertical cladding — Code of practice: the UK standard behind the headlaps, gauges and battens the makers' specifications set; its tables are not reproduced here
Inputs used
- Roof Area, Measured on the Slope
- 860 sq ft
- Tile or Slate
- Marley Modern, interlocking, 420 × 330 mm (16.5 × 13 in)
- Tile or Slate Length (your product)
- 16.5 in
- Cover Width (your product)
- 11.5 in
- Headlap (your product)
- 3 in
- How It Is Laid (your product)
- Single lap: interlocking tiles and pantiles
- Ridge and Hip Tile Cover (your product)
- 18 in
- Ridge Length
- 33 ft
- Hip Length
- 0 ft
- Eaves Length
- 66 ft
- Verge Length
- 52 ft
- Rafter Length, Eaves to Ridge
- 13 ft
- Roof Slopes
- 2
- Batten Stock Length
- 12 ft
- Cutting Allowance (%)
- 5
Intermediate steps
- Batten gauge
- 13.58 in
- Covering capacity
- 0.92 tiles/ft²
- Tiles for the roof area, before cutting
- 794 tiles
- Cutting allowance
- 5 %
- Battens at the maker's coverage, area over gauge
- 759.79 ft
- Batten courses on each slope
- 13 courses
- Battens, total run
- 860 ft
- Battens in stock lengths, cut course by course
- 78 lengths
- Ridge tiles
- 23 tiles
- Hip tiles
- 0 tiles
- Eaves and top-course tiles or slates
- 0 tiles
- Tile-and-a-half or slate-and-a-half at verges
- 0 tiles
Confidence note: Marley Modern is counted at its 345 mm (13.6 in) maximum gauge, 420 mm (16.5 in) less its 75 mm (2.95 in) minimum headlap, and its 292 mm (11.5 in) cover width, as its specification gives them, and Marley's concrete ridge and hip tiles, 457 mm (18 in) long. The tiles are the slope area times the covering capacity, with the cutting allowance on top. The battens are counted course by course, the rafter over the gauge plus the eaves batten on every slope, each course in whole stock lengths.
What this calculation does not cover
- The headlap and gauge are the maker's minimum for the tile chosen, or the figures entered. Whether that lap suits this roof's pitch, rafter length and exposure is for the maker's specification and BS 5534 to settle, and a roof that needs more lap needs more tiles and battens than the preset shows.
- The batten courses are the rafter over the full gauge plus one. A set-out marks the gauge up from the eaves datum to the top batten and eases it so the courses come out even, which can save a course on a short rafter or need one more where the top batten sits close under the ridge.
- Each course is the slope's width taken in whole stock lengths, with its last short piece left over, because Marley asks for every fixed length to be at least 1.2 m (3.9 ft) and to span three rafters. On a hipped roof the courses shorten up each hip end and are counted here at the slope's mean width, joints must land on rafters and be staggered between courses, and counter-battens under a breathable membrane are a separate count.
- Valleys are not counted: a valley in valley tiles, a dry valley trough or a lead lining is its own order, and the tiles cut along it come out of the cutting allowance. Dry verge units, eaves vents and ridge fixing kits are bought as accessories and are not counted either.
- On a plain-tile or slate roof the tiles-and-a-half at the verges take the place of field tiles they are counted on top of, and the top courses along a mono-pitch roof or an abutment are not counted from the ridge; both are small next to the field.
- Tiles are counted, never weighed. A tiled roof is heavy, and whether the rafters, battens and walls can carry it is a structural check, which matters most when a lighter covering is being replaced.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-10-05 · v1.0.0
Regulatory standards & verification citations9
- Marley, Modern interlocking tile technical specification: 420 × 330 mm; minimum headlap 75 mm (22.5° and above); maximum gauge 345 mm; cover width 292 mm (nominal); covering capacity 9.9 tiles/m² at 75 mm headlap and 10.7 at 100 mm; battens required 2.9 lin.m/m² at 75 mm headlap and 3.1 at 100 mm; 38 × 25 mm battens to 450 mm rafter centres, 50 × 25 mm to 600 mm
- Marley technical specifications for Ludlow Major (420 × 330 mm, maximum gauge 345 mm, cover width 295 mm, 9.8 tiles/m² at 75 mm headlap), Edgemere (420 × 330 mm, 345 mm, 298 mm, 9.7 slates/m²) and Ludlow Plus (387 × 230 mm, maximum gauge 312 mm, cover width 204 mm, 15.7 tiles/m², 3.2 lin.m of batten/m²)
- Marley plain tile technical specifications: concrete plain tile 267 × 168 mm and Hawkins clay plain tile 265 × 165 mm; minimum headlap 65 mm on a roof; maximum gauge 100 mm on a roof; 60 tiles/m² and 10.0 lin.m of batten/m² at 100 mm gauge
- Marley (Kevin Taylor, Training and Technical Support Manager), setting out tiling battens: the maximum gauge is the full length of the tile less the minimum headlap (420 − 75 = 345 mm), never to be exceeded and usually eased so the gauge is even; marked up from the eaves course datum to the top batten under the ridge; plain tiles need an under-eaves batten, and room at the ridge for the top course, an additional batten and an eaves/tops tile; battens to BS 5534 are supplied in lengths of at least 3 m, typically 3.6 m or more, at least 1.2 m long and over three rafters when fixed
- Marley (Kevin Taylor), roof tile sizes, how many roof tiles per square metre: for a rough estimate multiply the size of the roof in square metres by the roof covering capacity, for example 100 m² of Marley Acme plain tiles at 60 a square metre, 100 × 60 = 6,000 tiles, with nothing added; a different gauge or headlap changes the figure
- Marley concrete plain eaves/top tile and tile-and-a-half: eaves have a double course throughout their length using purpose-made eaves tiles for the undercourse; the tile-and-a-half is required to achieve the broken bond laying pattern
- Marley ridge and hip tiles: angled hip and ridge tiles typically 245 or 260 mm across, in lengths of 450 mm for clay and 457 mm for concrete
- Bristile Roofing, Concrete Roof Tiles Technical Manual, Classic product specification: 440 × 335 × 35 mm; set-out 360 mm maximum; 9.26 tiles per m²; 2.5 ridges per lineal metre; 2.9 m of batten per m²; ridge capping is a tile used for both the ridge and hips; overlapping ridge tiles laid away from the prevailing wind; installation to AS 2050
- BS 5534:2014+A2:2018, Slating and tiling for pitched roofs and vertical cladding — Code of practice: the UK standard behind the headlaps, gauges and battens the makers' specifications set; its tables are not reproduced here
Cite this page
Your workspace
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Tools and safety for this job
To batten and tile or slate the roof. Generic types, no brands, no prices.
Protection this work requires
- Cutting or grinding concrete, masonry, screed, tile or fibre-cement board releases respirable silica: cut wet or extract at the tool, and wear a P2/N95 respirator at minimum — a nuisance dust mask does not filter it.
- Saws, grinders and breakers run above 85 dB, where hearing damage accumulates and does not recover: defenders or plugs for every cut, not just the long ones.
- Breakers and grinders cause permanent nerve damage: limit continuous trigger time, keep hands warm, and stop if fingers tingle or blanch.
- Boards, blocks and bagged material cause most lasting back injuries on small sites: two people or a lifter for full sheets, and never a bag on one shoulder up a ladder.
- Most fatal falls on small jobs are from under three metres: use a tower or a ladder tied at the top, and never work off the top two rungs.
Show the 5 tools this job needsHide tools
Essential
Chalk line
Claw hammer
Hand saw
Tape measure
Recommended
Angle grinder
Also needed as materials: chalk refill, cutting and diamond discs.
what each roofing tool is for, and the spec that decides which to buy where one does.