Tile Calculator and Cost Estimator

The tile calculator estimates the tile boxes, thinset bags, and grout bags for a floor. Tile boxes come from room area plus waste, divided by box coverage. Grout and thinset depend on tile size, joint width, and trowel notch, and they are based on the actual floor area.

Last reviewed September 2026Method & sources Report an error

Not to scale.

Tile Boxes Needed (with waste)

Includes a 10% waste allowance.

Shopping list

Tile9 boxes
Thinset mortar2 50 lb bags
Sanded grout1 25 lb bags

Breakdown
Tile Boxes Needed (with waste)	9
Floor Area	120 sq ft
Grout (25 lb bags)	1
Thinset Mortar (50 lb bags)	2
Estimated Cost (Tile)

How to Calculate Tile

Tile itself is estimated the usual way: room area plus a waste allowance for cuts, divided by the box's coverage (which varies by product - check your tile's packaging) and rounded up to a whole box. Grout is different: coverage per bag depends heavily on both tile size and joint width, since a floor of small tiles has far more total joint length per square foot than the same floor in large tile. Rather than approximate this, grout coverage here is pulled directly from CUSTOM Building Products' published Polyblend Sanded Grout coverage table, by your exact tile size and joint width. Thinset mortar coverage depends on the trowel's notch size - a larger notch spreads a thicker bed for a bigger, heavier tile, which covers less area per bag. Grout and thinset are both based on the actual floor area (not the waste-inflated tile purchase amount), since they're applied to the installed floor, not the spare cut-off tile.

Example: 12 ft × 10 ft floor, 12x12 in. tile, 1/4 in. joints

A 12 ft × 10 ft floor, 12x12 in. tile, 1/4 in. joints, standard 1/4x3/8 in. trowel, boxes covering 15 sq ft, 10% waste: 1. Floor area: 12 × 10 = 120 sq ft 2. With 10% waste: 120 × 1.10 = 132 sq ft 3. Tile boxes: 132 ÷ 15 = 8.8, rounded up to 9 boxes 4. Grout coverage (12x12 in. tile, 1/4 in. joint, per CUSTOM's Polyblend table): 177 sq ft per 25 lb bag 5. Grout bags: 120 ÷ 177 = 0.68, rounded up to 1 bag 6. Thinset coverage (standard trowel): 65 sq ft per 50 lb bag 7. Thinset bags: 120 ÷ 65 = 1.85, rounded up to 2 bags Switching to a 4.25x4.25 in. mosaic-style tile at the same 1/4 in. joint would drop grout coverage to 101 sq ft per bag. For this 120 sq ft floor, that means 2 bags instead of 1, purely from the smaller tile size, because 177 ÷ 101 is about 1.75 times the grout per square foot.

Tile: Compare Scenarios

Scenario	Tile Boxes Needed (with waste)	Floor Area	Grout (25 lb bags)	Thinset Mortar (50 lb bags)
Small (8×8 ft bathroom)	5	64 sq ft	1	1
Medium (12×10 ft kitchen)	9	120 sq ft	1	2
Large (20×15 ft open living area)	22	300 sq ft	2	5

What Is Tile?

A tile calculator estimates all three materials a tile floor needs - tile, thinset mortar, and grout - rather than just the tile itself. It's built around the fact that grout usage varies dramatically with tile size and joint width (a small-format tile with a wide joint can need several times more grout per square foot than a large tile with a narrow joint), which is exactly the detail a flat area-based grout estimate misses.

Tile: Pros and Cons

Pros

Grout coverage comes directly from a real manufacturer's published table by tile size and joint width, not a flat area-based guess
Covers all three materials (tile, thinset, grout) in one estimate instead of treating tile as the only material that matters
Tile box coverage stays a product-agnostic adjustable input, since it varies significantly between tile lines

Cons

The grout coverage table is specific to CUSTOM Building Products' Polyblend Sanded Grout - a different grout brand, an unsanded or epoxy grout, or a different tile thickness than the table assumes will cover somewhat differently
Thinset coverage by trowel notch is a general industry planning figure, not tied to one specific product's published table, since coverage varies by mortar brand and substrate
Doesn't account for a diagonal or herringbone layout's extra cut waste beyond the adjustable waste percentage - increase that input for a complex pattern

Tile: What a Pro Checks

Match trowel notch size to tile size, not habit - a small mosaic tile needs a smaller notch (a thinner mortar bed) than a large-format tile, which needs a bigger notch for full, even support underneath it.
Planning a diagonal or herringbone layout? Bump the waste percentage above the default before you order - the extra angled cuts use noticeably more tile than a straight layout does.
Order grout by your actual joint width and tile size together, not tile size alone - the same tile can need very different amounts of grout depending on how wide the joints are set.

Frequently Asked Questions

How much grout do I need for my tile floor?

It depends heavily on tile size and joint width - per CUSTOM Building Products' Polyblend Sanded Grout coverage table, a 12x12 in. tile with a 1/4 in. joint covers about 177 sq ft per 25 lb bag, while a much smaller 4.25x4.25 in. tile at the same joint width covers only about 101 sq ft per bag. Smaller tile means more total joint length per square foot of floor, and more grout.

What trowel notch size should I use for thinset?

Notch size scales with tile size: a 1/4 x 1/4 in. notch suits small-format and mosaic tile, a 1/4 x 3/8 in. notch is standard for most floor tile, and a 1/2 x 1/2 in. (or a large-format-specific trowel) is used for large-format tile that needs a thicker, more even mortar bed. Check your tile manufacturer's installation instructions for their specific recommendation.

Why is thinset based on floor area, not the tile-with-waste amount?

Because thinset and grout go under and between the tile that's actually installed - the extra tile purchased to cover future cuts and breakage doesn't need its own mortar or grout, since it isn't part of the finished floor.

Does a bigger grout joint always mean more grout?

Yes, for a given tile size - looking at the 12x12 in. row of the coverage table, a 1/8 in. joint covers 348 sq ft per bag, while a 1/2 in. joint on the same tile only covers 92 sq ft per bag, since wider joints hold proportionally more grout volume.

What's the difference between sanded and unsanded grout?

Sanded grout (used for this calculator's coverage figures) is typically used for joints 1/8 in. and wider, since the sand aggregate helps prevent shrinkage and cracking in a wider joint. Unsanded grout is generally used for narrower joints (under 1/8 in.) or on tile surfaces that could be scratched by sand, such as polished stone.

Sources

CUSTOM Building Products Polyblend Sanded Grout Technical Data Sheet (TDS-129) - coverage table by tile size and joint width (opens in a new tab)

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