Flooring Tile Calculator

Purpose and model boundary

This calculator estimates the flooring to buy for the rooms of a floor plan you draw. Draw the outline, interior walls, windows and doors; then select each room in the Materials panel, choose Tile, Plank, Carpet, Sheet vinyl or None, and enter that room's product. Lay flooring lays the selected room's tiles, planks or roll strips. The spreadsheet returns pieces, boxes, roll length and tile-setting bags room by room and in total. Dividing a room's area by a tile's area and adding a percentage miscounts cut pieces at walls, islands and angled corners; here the pieces are laid and counted. It does not cover transitions at doorways, underlayment or pad as separate quantities, diagonal or herringbone patterns, pricing or labour.

Inputs and units

The drawing is the first input. The drawing tool finds the rooms and writes one row per room (its ID, floor area and enclosing-wall length), one row per wall side of every room, and one row per window and per door with its width and the room it belongs to. Each room's floor area is its face less any exclusions inside it, such as columns, islands or cabinets. The outline is also sent as its corner points, and up to five islands or columns inside the floor as exclusions. Draw the rooms to the finished wall faces; the wall thickness shown in 3D is for display only. Each exclusion can carry a height, set by double-clicking it on the drawing (blank is full height); it is carried for the drawing and its 3D view only, and no figure reads it, since the floor leaves out every exclusion whatever its height.

Each room's floor is chosen in the Materials panel: Tile, Plank, Carpet, Sheet vinyl or None, matched exactly, capitals included. That room's product dimensions, waste and package size are edited in the same panel; a different room may use a different product.

Lay flooring lays the selected room on the drawing. Calculate first lays every room that is not current, then sends one layout row per room: tile and plank rooms carry pieces laid and pieces including waste; carpet and sheet vinyl rooms carry strip count and the total strip length. A room with None carries no counts.

The inputs beside the drawing are:

• Tile setting: thinset coverage per bag, 90 sq ft or 8.4 square metres; grout coverage per bag, 150 sq ft or 13.935456 square metres. Tile size, joint, per-box count and waste belong to the selected room in Materials.
• Plank size, per-box count and waste belong to the selected room in Materials. Planks are butted, with no joint.
• Carpet and sheet vinyl roll width and waste belong to the selected room in Materials; the default width is 12 ft or 3.6576 m, with 10% waste.
• Ordering: Rooms share boxes and bags, No by default. Yes orders the boxes and bags on the plan's totals; No orders them room by room.

Piece sizes and joints are in inches under US and centimetres under Metric, roll widths in feet or metres. Each unit system has its own sizes and coverages: the Metric tile and thinset coverage are their own figures, and every other Metric default is the exact conversion of its US default. Every default is a typical figure or an assumption to review; use your product's sizes, its box count and the coverage on the bag.

The heights are set on the drawing or in the tables under it: one wall height for the whole plan, set with the drawing's Wall height button; each window's height and sill height; and each door's height. Lengths and heights are in feet under US and metres under Metric. The spreadsheet takes a wall height from 6 to 20 ft (1.80 to 6.00 m), a window at least 1 ft (0.30 m) tall on a sill of zero or more, and a door at least 5 ft (1.50 m) tall; these are the drawing tool's ranges, a product range rather than a code requirement. On the page the drawing accepts the wall heights valid in both unit systems, 6 to about 19.68 ft (1.83 to 6.00 m), so a unit switch never leaves the wall out of range; in the same way it asks for a window at least 1 ft (0.3048 m) and a door at least 5 ft (1.524 m) tall in both systems, so in Metric it refuses a 0.30 m window or a 1.50 m door that the spreadsheet alone would take. A new door starts at 6 ft 8 in or 2.03 m, no higher than the wall, and a new window at 4 ft or 1.20 m on a 3 ft or 0.90 m sill, the drawing tool's default heights.

Where the drawn values come from

Each room's floor area and enclosing-wall length come from the drawing tool's room detection, and each wall's length and each window's and door's width and room come from the drawing. The spreadsheet measures the outline's area from the corner points itself, and checks that the room areas add up to the floor area and that every wall, window and door belongs to a listed room.

Governing relationships

Tiles and planks are laid, not divided. For each tile or plank room the drawing sends its pieces laid and its pieces to buy:

Pieces to buy = pieces laid × (1 + waste), rounded up, exactly in whole numbers

Boxes = pieces to buy ÷ pieces per box, rounded up

For each tiled room, on its net floor area:

Thinset bags = floor area ÷ thinset coverage per bag, rounded up

Grout bags = floor area ÷ grout coverage per bag, rounded up

For each carpet or sheet vinyl room, each room its own cut off the roll:

Roll length = total laid strip length × (1 + that room's roll waste), rounded up to whole feet or metres

The totals add the rooms: tiles laid and to buy over the tile rooms, planks over the plank rooms, the carpet and sheet vinyl lengths over their rooms, and the floor area covered over every room whose floor is not None. When rooms share boxes and bags, the tile boxes are the tiles to buy over tiles per box, the plank boxes likewise, and the thinset and grout bags the tiled rooms' total area over the coverage, each rounded up once; otherwise each total adds the rooms' own rounded figures, so rooms do not share a box.

Nothing else is rounded, except that each waste is read to millionths of a percent, as the drawing reads it, and the height checks compare at six decimals; the shown figures are the display of the full values. Every division is taken at six decimals before it is rounded up, so a figure that is whole on paper stays whole. Carpet pad is ordered to the same length as the carpet.

How the pieces are counted

The drawing tool lays the chosen tile or plank in rows from the top-left of each room's bounding box (you may move the start and turn the rows), clips the rows at the walls and around exclusions, and counts every whole piece and every cut. Cut pieces are taken from the offcuts of earlier cuts where a straight-cut rectangle fits (no rotation, no saw kerf), so the count is labelled an estimate unless it equals the least possible count. Pieces to buy add your waste allowance and round up. Patterns are straight or offset rows: tiles start straight and planks at a one-third offset, and either can be changed on the drawing. The drawing tool checks at most 10,000 piece positions in a room; a small piece over a large room is refused on the drawing with its message, and no count is sent.

The spreadsheet checks the counts it is sent: they must be whole numbers, at most 10,000 pieces laid in a room; the pieces to buy must equal the pieces laid plus the waste, rounded up, worked in whole numbers as the drawing tool works it; and a room laid with no joint (every plank room, and a tile room with a zero joint) must have at least the pieces its floor area needs, allowing for the drawing tool's contact tolerance. The drawing tool leaves out a piece that would meet the floor only along a sliver no wider than its contact tolerance, 0.00001 in (0.0000254 cm), so a floor may be covered short of its area by at most one such sliver along a piece's longer side for each of the 10,000 positions it examines. For a 48 by 7.5 in plank the allowance is 10,000 × 0.00001 × 48 ÷ 144 = 0.0333 sq ft. A tiled room with a joint has no such check: with the joints, a shifted start can truly need fewer tiles than the floor area divided by one tile's area.

Calculation sequence

1. The spreadsheet checks the drawing, the tables, the heights, the room floors, the layout rows, the inputs of every kind of floor in use and the piece counts, in the order the status list below gives.
2. For each room it reads its floor and, for a tile or plank room, its laid counts by its ID, then works out its boxes, its thinset and grout bags or its roll length.
3. It adds the rooms into the totals, room by room or, when rooms share, on the totals.

The default plan works through as follows: one 20 by 15 ft room in 12 by 12 in tile with a 1/8 in joint is laid as 19 × 14 = 266 whole tiles and 34 cut tiles, 300 tiles laid; 300 × 1.10 = 330 tiles to buy, 330 ÷ 10 = 33 boxes, 300 ÷ 90 = 3.33 → 4 bags of thinset and 300 ÷ 150 = 2 bags of grout, on 300 sq ft of floor.

Worked example 11.4.3.1 lays one room in plank, 60 planks laid, 66 to buy and 9 boxes, and the other in tile, 150 tiles laid, 165 to buy and 17 boxes. Worked example 11.4.3.4 lays 24 by 12 in tile at a one-third offset around an island: 99 whole tiles and 43 cut cells at the walls, the island and the angled wall, the cuts packed into 30 tiles, so 129 tiles are laid and 142 bought, in 24 boxes. Worked example 11.4.3.2 orders 18 ft of carpet for a 192 sq ft room off a 12 ft roll: 192 × 1.10 ÷ 12 = 17.6 → 18.

Outputs and interpretation

• Tile: the tile boxes, the tiles to buy and the tiles laid, and the thinset and grout bags.
• Plank: the plank boxes, the planks to buy and the planks laid.
• Roll goods: the carpet and the sheet vinyl to order, in whole feet or metres.
• From the drawing: the floor area covered, the net floor area, the gross area and the area of each island or column.
• By room: one row per room with its floor, its net area, the pieces laid and to buy, its boxes, its roll length and its thinset and grout bags; a cell that does not apply to the room's floor is blank. While rooms share boxes and bags, the boxes and bags columns are blank, because the totals are ordered together. The headings carry the units of the system the drawing was sent in.

A laid count is the drawing's own: it is usually higher than the area divided by a piece, because each room's edges and every exclusion take cut pieces. It can also equal that figure or fall below it. The default room lays 300 tiles on 300 sq ft of 1 sq ft tiles; worked example 11.4.3.1's plank room, whose cuts all pack into whole planks, lays exactly 60 planks, 21,600 ÷ 360 sq in; and a tile room with a joint can lay fewer, because the joints take part of the floor.

The 3D view draws the walls you drew at the wall height, with the door and window openings cut at their sills and heights, and a tinted floor per room. The laid tiles and planks show on the plan only. It is for checking the drawing; it shows no figures, sends nothing and changes nothing.

Validation and status logic

The status reads OK or NOT VALID with what to fix. While it is NOT VALID every quantity reads zero and the By room rows are blank; the drawn areas still show. There is no CHECK state. The first problem found is reported, in this order:

1. NOT VALID: choose US or Metric
2. NOT VALID: draw at least three outline points
3. NOT VALID: every outline point needs both coordinates
4. NOT VALID: every point of exclusion 1 needs both coordinates
5. NOT VALID: every point of exclusion 2 needs both coordinates
6. NOT VALID: every point of exclusion 3 needs both coordinates
7. NOT VALID: every point of exclusion 4 needs both coordinates
8. NOT VALID: every point of exclusion 5 needs both coordinates
9. NOT VALID: each exclusion needs zero or at least three complete points
10. NOT VALID: outline and exclusion points must fill consecutive rows, with no blank row between them
11. NOT VALID: the floor outline encloses no area
12. NOT VALID: the exclusions leave no floor area
13. NOT VALID: room, wall, window and door rows must be complete, with lengths above zero and no negative area, and fill consecutive rows with no blank row between them
14. NOT VALID: the room areas do not add up to the floor area drawn
15. NOT VALID: every room must be listed once, and every wall, window and door must belong to a listed room
16. NOT VALID: wall, window and door IDs must each be listed once, and no ID or room ID may contain *, ? or ~ or begin with <, > or =
17. NOT VALID: the wall height must be from 6 to 20 ft (US) or from 1.80 to 6.00 m (Metric)
18. NOT VALID: every window needs a height of at least 1 ft (US) or 0.30 m (Metric)
19. NOT VALID: every window needs a sill height of zero or more
20. NOT VALID: every door needs a height of at least 5 ft (US) or 1.50 m (Metric)
21. NOT VALID: a window or door reaches above the wall height
22. NOT VALID: an exclusion height must be greater than zero; leave it blank for full height
23. NOT VALID: an exclusion height is given for an exclusion that is not drawn
24. NOT VALID: choose a material for every room: Tile, Plank, Carpet, Sheet vinyl or None
25. NOT VALID: the layout rows must list every room once, by its ID, and fill consecutive rows with no blank row between them
26. NOT VALID: choose Yes or No for sharing boxes between rooms
27. NOT VALID: every tile room needs a tile length and width greater than zero
28. NOT VALID: every tile room needs a grout joint of zero or more
29. NOT VALID: every tile room needs a whole number of tiles per box, at least one
30. NOT VALID: every tile room needs a waste between 0% and 50%
31. NOT VALID: a tile room needs thinset and grout coverage greater than zero
32. NOT VALID: every plank room needs a plank length and width greater than zero, a whole number of planks per box, at least one, and a waste between 0% and 50%
33. NOT VALID: every carpet and sheet vinyl room needs a roll width greater than zero and a roll waste between 0% and 100%
34. NOT VALID: every tile and plank room needs its piece counts from Lay flooring on the drawing
35. NOT VALID: every carpet and sheet vinyl room needs its strips from Lay flooring on the drawing
36. NOT VALID: only tile and plank rooms carry pieces including waste, only carpet and sheet vinyl rooms a strip length, and a room with no floor carries no counts
37. NOT VALID: piece counts must be whole numbers of 0 or more, with at most 10,000 pieces laid in a room
38. NOT VALID: strip counts must be whole numbers from 1 to 1,000 and strip lengths above zero
39. NOT VALID: a room's pieces to buy must be its pieces laid plus the waste, rounded up
40. NOT VALID: a room laid with no joint has fewer pieces than its floor area needs
41. NOT VALID: a carpet or sheet vinyl room's strips do not cover its floor area

The inputs of a kind of floor are checked only while a room uses it, so an input for a floor no room has never stops the results. The height limits are the drawing tool's own: the spreadsheet holds a direct caller to the drawing tool's range for each unit system (items 17 to 21), and the page narrows the wall and the openings to the ranges valid in both systems. A room ID and a floor must match exactly, case included, and two IDs that differ only in case count as one ID listed twice. An ID or room ID carrying *, ? or ~ or a leading <, > or = is refused, by item 15 or item 16: a room ID containing * or ?, or beginning with <, > or =, can fail item 15's membership check first, because that check reads it as a pattern. The layout counts are the drawing's: on the page Lay flooring writes every room once, with whole piece counts for tile and plank, or whole strip counts and total strip length for carpet and sheet vinyl. Items 34 to 41 check those counts and their room types; an invalid product size, waste, or room over the drawing tool's limit is refused on the drawing before anything is sent. The spreadsheet checks the rows' completeness, IDs, room areas, heights, floors and counts; it does not check that the counts equal a real layout of the drawn rooms, which the drawing tool lays on the page.

Assumptions and limitations

• Roll strips are laid across each room rather than inferred from its area; seams and cut placement still need on-site planning.
• Thinset and grout coverage depend on the trowel notch, the tile's size and thickness and the joint width, so read them from the bag's chart.
• The one-third offset default for planks and the straight default for tiles are layout choices; tiles with a side over 15 in should not be offset by more than a third.
• Door transitions are not counted yet.
• Cut pieces are reused only within the room they were cut in, without rotation and without a saw kerf.
• The wall, door and window heights shape only the 3D view and must each be within its range; no flooring figure reads a height. The wall height converts with the units when you switch between US and Metric, and a door or window with no height in the new units gets the defaults.
• Nothing is saved between visits. Export keeps the drawing and each room's layout start and direction, but not the heights or each room's floor, which must be chosen again after an import; the room areas and enclosing lengths come from the drawing tool's room detection.

Restrictions and non-computing states

The spreadsheet computes nothing while the status is NOT VALID: every quantity reads zero and the By room rows are blank. Edits on the page stay local until Calculate is pressed, and Calculate lays each floor first whenever it is not laid or is out of date. A plan whose rooms all have None has nothing to lay and calculates at once.

Errors and warnings

Each NOT VALID line above names the input to fix. A height outside the drawing's limits, or a blank opening height, is refused, because the opening must still fit the wall. If the drawing cannot lay the floor (for example with a piece or roll width of zero, a waste outside its floor type's range, or a small piece over a large room), Calculate sends nothing and the drawing tool's own message says why.

Sources and further reading

• National Institute of Standards and Technology, NIST Guide to the SI, Appendix B.9, "Factors for units listed by kind of quantity or field of science". nist.gov. The inch is exactly 2.54 cm, the foot 0.3048 m and the square foot 0.09290304 m²: the exact factors behind the two unit systems and the Metric defaults that are conversions of the US ones.
• Custom Building Products, VersaBond Professional Tile Mortar. custombuildingproducts.com. The coverage per 50 lb bag by trowel notch: 90 to 100 sq ft (8.4 to 9.3 m²) with a 1/4 by 1/4 by 1/4 in square notch, and 60 to 67 sq ft with a 1/4 by 3/8 by 1/4 in notch.
• Custom Building Products, Polyblend Plus Sanded Grout. custombuildingproducts.com. The coverage per 25 lb bag by tile size and joint width, in its chart for estimating purposes.
• Ceramic Tile Education Foundation (S. Carothers), "Offsets, Grout Joints and Customer Expectations". ceramictilefoundation.org. The running bond offset limit of 33% for tiles with a side over 15 in, and minimum grout joint widths.

90 sq ft and 8.4 m² of thinset per bag are the low end of the manufacturer's stated range for a 1/4 in square notch (cited); the piece sizes, box counts, wastes, roll widths and grout coverage are the calculator's own typical figures, and each unit system has its own. Use your product's sizes and box count and the coverage on the bag. These sources describe units, products and practice and certify no particular result.