Enter room and tile dimensions to estimate materials, including wastage, optional non-tiled cutouts, and estimated cost.
How this calculator works
Cutouts are subtracted from the room area, then the wastage allowance is applied to the remaining area, then the result is divided by the area of one tile.
tiles = ceil( ( (room L × room W) − cutouts ) × (1 + wastage%) ÷ (tile L × tile W) )boxes = ceil( tiles ÷ tiles_per_box ) (only when "tiles per box" is set)
- All units are converted to feet internally before computing area.
- 10% wastage is the trade default for straight-laid square tiles. Bump to 15% for diagonals; 20% for pattern layouts (herringbone, basket-weave) or large-format tiles 24 inches and up.
Common questions
How much wastage should I plan for tile?
10% is the trade default for straight-laid square tiles. Bump to 15% for diagonal layouts. Push to 20% for pattern layouts — herringbone, basket-weave, or anything with directional grain — and for large-format tiles 24 inches and up, where every cut is bigger and harder to reuse.
Should I round up to whole boxes?
Yes. Dye lots can vary between batches, so order all your tile at once and round up to whole boxes. Keep at least one spare box for future repairs.
Does this calculator account for grout joints?
No — it uses the nominal tile size to compute count. Grout joints (typically 1/16″ to 1/4″) effectively cover slightly more area per tile, but the wastage allowance absorbs the difference.
Tile is sold by the box and dye-lot-matched within the production run. Run short and the box you go back for is a different lot — a slightly different beige, slightly different glaze depth, and now your bathroom has a visible split where the original lot ends. Run long and you’ve got a half-box of expensive porcelain you’ll never use, and the supply house won’t take it back. This calculator returns the tile count for the room you described, the box count rounded up, and a waste allowance keyed to your layout so the dye lot covers the whole job in one trip.
What you’ll get
Enter room length and width, choose a tile size (12×12, 12×24, mosaic sheet, etc.), set grout spacing, and tune the waste percentage. The calculator returns net floor area, tile-equivalent count, box count rounded up, and an estimated cost if you supply a per-box or per-tile rate.
A sample bathroom
Say you’re tiling an 8 ft × 10 ft bathroom with 12×12 inch porcelain at 1/8 inch grout. Floor area is straight geometry; each 12×12 tile covers 1 ft²:
Add 10% waste for square cuts:
Most 12×12 porcelain ships at 12 tiles per box (about 12 ft² per box). 88 ÷ 12 = 7.3, so you order 8 boxes — 96 tiles total. The 8 extra are your dye-lot insurance for the next time a tile cracks during install or three years from now when a hairline shows up at a seam.
Waste, and where the defaults come from
10% is the supply-house norm for a square-cut layout (tiles parallel to the walls). Bump to 15% if you’re laying on a diagonal; every cut is a triangle and the offcuts don’t always reuse. Push to 20% for pattern layouts — herringbone, basket-weave, or anything with directional grain — and the same 20% for large-format tiles 24 inches and up, where every cut is bigger and harder to make useful. Add another 5% on top if you’ve never laid this size or this pattern before. The waste pays for itself the first time you crack one feeding it through the wet saw.
When to lean on it, when not to
This is a single-rectangular-room calculator. It handles bathroom floors, kitchen splashbacks of regular shape, and small entryways well. It is not the right tool for L-shaped rooms (calculate each rectangle separately and add), niches and curbs that pull from a separate cut, mosaic sheets where the math runs in sheets per ft² rather than tiles, or anywhere a feature strip changes the count mid-room. For those, draw the layout to scale on graph paper and count the tiles directly.
Thinset, grout, and edging trim are not in the calculator — figure one bag of modified thinset per 50 ft² of porcelain, one 25-lb bag of unsanded grout per 100 ft² with 1/8 inch joints, and Schluter trim by the linear foot at the exposed edges.
If you’re scoping a whole-bathroom remodel, a heated-floor install where the underlayment changes the spec, or anywhere a tile pattern crosses a transition between materials, a sit-down with a tile contractor who can plan the layout from the centre line is usually cheaper than reordering the dye lot you just lost.
Other calculators on this site
If you’re scoping a whole project, you’ll usually need more than one of these. They share the same approach — plain math, honest about edge cases, with the practical notes someone who has done the work would actually need.
- Asphalt Calculator. Tonnage for a driveway, parking patch, or walkway pour, including the depth-to-tonnage curve a supplier will quote against.
- Concrete Pour Calculator. Cubic yards of concrete for a slab, footing, or post hole, plus the waste factor most pours actually need.
- Drywall Calculator. Sheets of drywall and bundles of mud for a renovation room, plus the cut and waste allowance.
- Excavation Calculator. Cubic yards of dirt to remove for a basement, pool, or footing — including the bulking factor that surprises first-timers.
- Fence Calculator. Lineal feet of fence, post count, rails, and gates for a property line that is rarely perfectly straight.
- Fill Calculator. Cubic yards of fill for a regrade, a backyard level, or a low spot, plus a sensible compaction factor.
- Lumber Calculator. Board feet for a deck, frame, or addition, in the rough framing pattern a supplier will price against.
- Paint Calculator. Gallons of paint for a room, plus the coverage difference between primed and unprimed surfaces.
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