Tile & Grout Estimator
Count the tiles for a floor or wall, including a waste allowance for your layout pattern, then estimate boxes to buy, grout by weight and thin-set mortar bags, with a material cost.
Written by Suhaib Hassan. Coverage figures are typical; the bag label wins. Our methodology.
It divides the area by the tile plus joint size, adds waste, then estimates grout from the joint volume and mortar from notch coverage.
Tile lots vary in colour, so it pays to buy everything once. This shows a safe order quantity for the whole job.
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Grout coverage guide
Square feet covered by one 25 lb bag of grout at 3/8 in tile thickness, from the same formula as the calculator including a 25% allowance for waste. Bag labels vary by brand.
| Tile size | 1/16 in joint | 1/8 in joint | 3/16 in joint | 1/4 in joint | Typical notch |
|---|
Large-format tile (any edge 15 in or more) needs a larger notch, a flat substrate and careful lippage control. Follow the tile and mortar manufacturer's instructions.
How the estimate is worked out
Tiles
tiles = ⌈ area ÷ ((L + j)(W + j) ÷ 144) × (1 + waste) ⌉Grout
lb = area × 144(L + W)·T·j ÷ (L·W) ÷ 1728 × 112 × 1.25Thin-set
bags = ⌈ area × (1 + waste) ÷ coverage per 50 lb bag ⌉L and W are the tile length and width in inches, T is thickness and j is the joint width. 112 lb/ft³ is a typical density for packed sanded grout.
Waste by pattern
Keep a few spare tiles for future repairs, since later batches may differ in shade.
Worked examples
Illustrative jobs, each checked by hand. The first is the default setup.
12 × 10 ft floor, 12 in tile
1/8 in joint, straight grid (10% waste), 10 tiles per box.
120 ÷ 1.0210 = 117.5 tiles
× 1.10 = 129.3 → 130 tiles
130 ÷ 10 → 13 boxes
Grout for that floor
12 × 12 in, 3/8 in thick, 1/8 in joint.
= 1.125 in³ per ft²
× 120 ft² ÷ 1728 × 112 × 1.25 = 10.9 lb
→ one 25 lb bag
Subway tile backsplash
30 sq ft, 3 × 6 in, 1/16 in joint, running bond (12%).
= 0.1289 ft² each
30 ÷ 0.1289 × 1.12 = 260.7 → 261 tiles
How many tiles do I need?
- Measure the area to be tiled, or enter a known total in square feet.
- Enter the tile size and the grout joint, since the joint slightly increases the space each tile covers.
- Choose your layout. Diagonal and herringbone patterns waste more than a straight grid.
- Round up to whole boxes and buy from a single lot for consistent colour.
This is an estimate. Uneven floors, walls with many niches, and patterns that need matching can all raise waste, so ask your installer for a final count.
By Suhaib Hassan · Reviewed 29 September 2026 · How CalculatePilot verifies formulas →
Sources
- Tile Council of North America (TCNA), Handbook for Ceramic, Glass, and Stone Tile Installation, including guidance on large-format tile.
- ANSI A108 and A118, American National Standards for installation and setting materials.
Frequently asked questions
How much extra tile should I buy?
Ten percent is the usual minimum for a straight layout. Add more for diagonal, herringbone or mosaic patterns, and for rooms with many corners or obstacles.
How much grout do I need?
It depends on tile size, thickness and joint width. Small tiles and wide joints need much more grout than large tiles with narrow joints. This tool works from the joint volume and adds 25% for waste and uneven surfaces.
Sanded or unsanded grout?
Sanded grout is normally used for joints of 1/8 inch and wider because it resists shrinking and cracking. Unsanded grout suits narrower joints and soft or polished stone that sand could scratch. Epoxy grout resists stains and chemicals.
What trowel notch should I use?
Small tiles usually take a 1/4 in square notch, mid-size tiles a 1/4 × 3/8 in notch, and large-format tiles a 1/2 in square notch or larger. Always follow the mortar bag instructions and check for full coverage under the tile.
Why does tile thickness matter?
Thicker tile has deeper joints, so it takes more grout. The tile-and-joint size also changes how many tiles fit in an area.
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