Tile & Ceramic Calculator

The tile calculator answers the single question every renovation starts with: how many tiles do I buy? Divide the room area by the tile area, add a wastage allowance (always round up — you can't return half a tile), then divide by the tiles-per-box count to get a purchase order. The grout estimate uses the manufacturer-published average of 0.4 kg per square metre for 3 mm joints — wider joints or larger format tiles need a higher coefficient.

Core formula

Convert tile dimensions to square metres, divide the room area by that figure, and bump up by wastage.

Total Tiles = ⌈(Room Area ÷ Tile Area) × (1 + Wastage%)⌉ | Boxes = ⌈Total Tiles ÷ Tiles per Box⌉ | Grout (kg) = Area × 0.4

Worked example — a 4 × 3 m room with 60 × 60 cm tiles

Inputs: area = 4 × 3 m, tile = 60 × 60 cm, wastage = 10%, tiles per box = 4.

1. Room area = 4 × 3 = 12 m²
2. Tile area = 0.60 × 0.60 = 0.36 m²
3. Exact tiles = 12 / 0.36 = 33.33
4. With wastage = 33.33 × 1.10 = 36.67 → ceil = 37 tiles
5. Total boxes = ⌈37 / 4⌉ = 10 boxes
6. Grout = 12 × 0.4 = 4.8 kg

Common mistakes

• Measuring area without deducting large openings — or deducting small ones that in practice are not saved, because cutting wastes the tile around them.
• Ignoring wastage entirely: edge cuts consume around 10% even on a simple straight lay.
• Using one wastage rate for every pattern — diagonal and herringbone lays need 15–20% rather than 10%.
• Confusing tile count with box count: boxes are sold whole, and any remainder always rounds up.

Before you order

• Order the whole quantity from a single production batch: two batches differ in shade in a way that only shows after laying.
• Keep one full box after the job — replacing a cracked tile a year later from another batch is visible.
• Check the actual tile size, not the nominal one: '60x60' ships at sizes that differ by millimetres between suppliers, and the gap accumulates over a large area.
• If the shipment is imported, add the lead time to your schedule: running one box short mid-installation stops the job for weeks, not days.