Tile Calculator

Tiles, thinset, and grout with the right waste factor for your layout. Updated for 2026.

Last reviewed July 2026 · Free · Nothing you enter is stored

How this calculator works

Tile count = area × pieces per sq ft × (1 + waste). Thinset coverage averages 85 sq ft per 50 lb bag with a 1/4" notch trowel (less for large-format with back-buttering). Grout runs 100–200 sq ft per 25 lb bag depending on tile size and joint width — small tiles use far more grout per square foot.

The waste allowance

The waste percentages this calculator offers — about 10% for a straight lay, about 15% for a diagonal, and 15 to 20% for herringbone and other complex patterns — are common trade practice rather than a published standard. They are widely repeated in the trade and they hold up in practice, but they could not be verified against the TCNA Handbook, so treat them as experienced guidance rather than a specification. The logic behind them is straightforward: every cut against a wall or an angle produces an offcut, and the more angles a pattern contains the less of each cut tile ends up back on the floor. A diagonal layout cuts every perimeter tile. Herringbone consumes full tiles at every edge and around every obstruction. Beyond the waste allowance, put a box aside for repairs, because shade varies between production runs and a matching replacement is very hard to find later.

Tiles per square foot, with one adjustment

The count itself is arithmetic. A twelve by twelve tile is one per square foot. A six by six is four. An eighteen by eighteen works out at 0.44 per square foot, which is why an eighteen inch tile covers more than twice the area of a twelve.

The adjustment is the grout joint. A tile is laid on a module equal to its actual dimension plus the joint width, so a twelve inch tile with a three-sixteenths joint occupies a little over twelve inches of floor. Across a large room that difference accumulates into roughly a tile's worth of coverage, in your favour. For precise counts, particularly on small tile with wide joints where the joint is a real fraction of the module, add the joint to the tile dimension before dividing into the area.

Nominal sizes are another source of drift. Many tiles sold as twelve by twelve actually measure slightly under, by design, so the joint takes up the difference. If you are counting closely on a large job, measure a tile out of the box rather than trusting the size on the label.

Thinset coverage follows the trowel

Thinset is bought by the bag and consumed by the trowel. Mapei publishes coverage by notch size for a fifty pound bag: a quarter by quarter by quarter inch square notch covers 80 to 100 square feet, a quarter by three-eighths by quarter notch covers 60 to 80, and a half by half by half notch covers 40 to 50. Moving up one notch size can halve the area a bag covers.

The notch is not a free choice. It is dictated by the tile, because the ridges have to collapse into full contact under the tile without starving the bond. Small format tile on a flat substrate works with a small notch. Large format tile needs a larger notch to bridge the substrate and reach adequate coverage under the tile, and usually needs back-buttering as well.

Back-buttering is where budgets slip. Skimming the back of each tile in addition to the notched bed puts noticeably more mortar into the floor than the notch chart alone suggests, and coverage falls well below the quoted figure. If your tile calls for a half inch notch and back-buttering, plan against the low end of the chart and then add to it.

Grout is where generic coverage numbers fall apart

Any single figure for grout coverage is close to meaningless without three other pieces of information: tile size, joint width and product chemistry. The spread between products is enormous. Laticrete's coverage chart for a twelve by twelve tile three-eighths of an inch thick gives 159 square feet per unit for an epoxy grout at a one-eighth inch joint, and 388 square feet per unit for a cement-based grout at the same joint. That is a factor of more than two between two products doing the same job in the same joint.

Joint width moves the number just as hard. On the same chart, one product covers 206 square feet at a one-eighth inch joint but only 138 square feet at three-sixteenths. Widening the joint by a sixteenth of an inch cuts coverage by around a third, because the volume of the joint scales with its width across the entire floor.

The practical consequence is that grout has to be estimated against the specific product's chart, at your tile size and your actual joint width, and not against a number remembered from a previous job. If you change the tile or the joint after buying, redo the estimate.

Ordering: dye lots and pattern layouts

Tile is manufactured in production runs, and shade varies between them. Boxes carry a dye lot or shade code, and two boxes of the same product from different lots can differ enough to be visible under raking light across a finished floor. Ordering the full quantity in one purchase, from one lot, is the only reliable way to avoid that.

Pattern layouts make this more pressing rather than less. A herringbone or diagonal layout consumes more full tiles to produce each usable cut piece, so the quantity you need is higher and the chance of running short before the end is higher with it. Coming up two boxes short on a herringbone floor and finding the replacement lot is a shade off is a genuinely bad outcome, because the mismatch usually lands somewhere visible.

For the same reason, keep the spare box rather than returning it. Repairs happen years later, a cracked tile needs a match, and the original lot will be long gone from the shelf by then. A box in the garage is cheap insurance against having to replace an entire floor because of one broken tile.

Thinset and grout coverage

Thinset coverage is per 50 lb bag by trowel notch. Grout coverage is per unit for a 12x12 tile 3/8 inch thick and shows how far the number moves with product type and joint width.

Thinset coverage by trowel notch from Mapei's published figures. Grout coverage from Laticrete's coverage chart for 12x12x3/8 tile. Large format tile requiring back-buttering will fall below the quoted thinset coverage.

What goes wrong ordering tile

Buying grout on a generic coverage figure. Coverage depends on tile size, joint width and product chemistry. On one published chart the same product covers 206 square feet at a 1/8 inch joint and 138 at 3/16, a drop of about a third.

Using a trowel notch that does not match the tile. Large format tile needs a bigger notch and usually back-buttering, which puts real coverage well below the number on the bag chart.

Ordering short of a full dye lot. Shade varies between production runs. Pattern layouts consume more full tiles per usable cut piece, so the risk of running out mid-floor and having to buy a second lot is highest exactly where a mismatch shows most.

Applying straight-lay waste to a pattern. Ten percent covers a straight lay. Diagonals run nearer fifteen and herringbone fifteen to twenty. These are trade convention rather than a published standard, so err upward on complex layouts.

Counting tiles without the grout joint. A tile occupies its own dimension plus the joint width. On small tile with wide joints that difference is a real fraction of the module and it shifts the count.

Frequently asked questions

Why your state changes the price (but not the quantity)

How much tile you need is physics — it doesn't care where you live. What it costs does. Labor rates, delivery distance, fuel, and local demand move installed prices by roughly 45 points from end to end: Arkansas, Mississippi, North Carolina sit near the bottom of the range, while Alaska, Hawaii, New York sit at the top. The Price this for selector at the top of the calculator applies a published construction cost index for your state to the 2026 national averages, so the dollar figures move and the material list stays put.

Treat the result as a budgeting range, not a quote. Two metros inside the same state can differ by more than the statewide index suggests, and a single busy contractor can outweigh both. See the full cost index for all 50 states and where the price data comes from.