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 to avoid

• Using 0% wastage on a real installation — even straight cuts produce offcuts; the safe minimum is 5–10%.
• Confusing tile dimensions in centimetres vs millimetres — 60 mm and 60 cm differ by a factor of 100.
• Ignoring patterns — diagonal layouts and herringbone need 15–20% wastage instead of 10%.
• Mixing batches — order all the tiles in one purchase to avoid colour-lot drift.

Tips for accurate estimates

• Buy one extra box for future repairs — discontinued tile lines are common.
• For L-shaped or irregular rooms, calculate each rectangle separately and add them.
• Wall tiles typically need less grout than floors because joints are tighter.
• Always confirm tiles-per-box with the supplier — it varies by brand and size.