Tile Calculator
Work out how many tiles and boxes to buy for a floor or wall, with an adjustable allowance for cuts and breakage (10 percent by default), plus an estimate of how much grout the job needs.
Your results
Worked example
A 12 m² bathroom floor with 30 cm by 60 cm tiles, a 3 mm grout gap, the waste field at 10 percent, and the grout depth field at 10 mm:
- Each tile covers, including its share of grout joint: (0.30 + 0.003) m × (0.60 + 0.003) m = 0.303 × 0.603 = 0.1827 m²
- Exact tiles: 12 ÷ 0.1827 = 65.68, so 66 tiles
- With the waste field at 10 percent: 65.68 × 1.10 = 72.25, so buy 73 tiles
- At 10 tiles per box: 73 ÷ 10 rounds up to 8 boxes
- Grout: (600 + 300) ÷ (600 × 300) × 3 mm gap × 10 mm depth from the grout depth field × 1.6 = 0.24 kg per m², times 12 m² = 2.9 kg in total
So the shopping list is 8 boxes of tile and roughly 3 kg of grout. Grout is sold in bags of about 2.3 kg, 4.5 kg, and 11.3 kg, so one 4.5 kg bag covers this job with some to spare.
How this calculator works
Tile counts here account for the grout joint, because the joint is part of the area each tile effectively covers:
The waste allowance, 10 percent by default and set in the field above, covers cuts at edges, breakage, and a few spares for future repairs. Use 15 percent for diagonal layouts and up to 20 percent for small rooms with many cuts. Grout is estimated with the standard manufacturer-style formula:
Tile dimensions are in millimetres in that formula. The grout depth comes from the field above and is 10 mm by default, and the mixed grout density factor is 1.6, which suit most cement-based grouts and standard tile thicknesses. Deep joints, thick natural stone, and epoxy grout all change the number, so check the coverage chart on your grout bag before a large purchase.
Common questions
Why does the grout gap change the tile count?
Every tile plus its surrounding joint covers slightly more area than the tile alone. On large-format tile with a thin joint the effect is small; on small mosaic-style tile with wide joints it can change the count by several percent, which is why this calculator includes it instead of ignoring it.
Is 10 percent waste always enough?
For straight layouts in simple rectangular rooms, yes, it is the industry standard allowance. Diagonal or herringbone patterns, rooms with many corners, and first-time tilers should set the waste field to 15 percent, or 20 percent for small, cut-heavy rooms. Having leftover tile from the same production batch is also your insurance for a future cracked tile, since dye lots vary.
How much grout should I actually buy?
Round up to the next bag size and keep the receipt; unopened bags are usually returnable. The estimate uses the grout depth in the field above, which starts at 10 mm. If your tile is thicker than about 10 mm, set the depth to your tile thickness and the estimate will follow.
Does this calculator work for wall tile and backsplashes?
Yes. Enter the wall area in square metres (height times width, minus windows and doors if they are large). Wall jobs often use smaller tile and thinner joints, so enter your real gap size.
Estimates only, based on the formulas and assumptions stated on this page, including the waste allowance and grout depth entered above (10 percent and 10 mm by default) and a grout density factor of 1.6. Actual needs vary with layout, tile thickness, and installer technique. Confirm quantities with your supplier or installer before ordering. Mississippi Maple accepts no liability for purchase decisions made using this calculator.