The calculator divides your floor or wall area by the tile size, adds a wastage allowance for cuts, and rounds up to whole boxes. Standard sizes (300×300, 600×600, 800×800 mm) are pre-loaded.
What is Tile?
Tile estimation comes down to: how much area, what size tile, and how much extra to allow for cuts at edges. The math is simple division, but the tricky part is the wastage allowance — 10% for straight-cut floor tiles, more for diagonal layouts or rooms with many corners.
Tiles are sold in boxes. The number of tiles per box depends on the size — 4 tiles per box of 600×600, 9 per box of 300×300. The calculator rounds up to whole boxes since you can't buy partial.
Always keep 1-2 spare boxes after the project. Tile colour batches change over time — matching exact shades for repairs after a few years can be impossible.
Rectified or non-rectified changes how the tiles sit, not how many you need. A rectified tile is ground to an exact size after firing, so a row of them lines up with a very narrow joint. A non-rectified tile carries the wider size tolerance the standard allows, so it needs a slightly wider joint to absorb that variation. IS 15622 sets separate dimensional tolerances for the two.
Water absorption decides where a tile can go. IS 15622:2017 classifies pressed ceramic tiles into groups BIa, BIb, BIIa, BIIb and BIII by how much water the body soaks up, following the ISO 13006 classification: BIa absorbs 0.5% or less, BIb over 0.5% up to 3%, BIIa over 3% up to 6%, BIIb over 6% up to 10%, and BIII more than 10%. BIa is the fully vitrified body sold in India as "vitrified" and elsewhere as porcelain — the one to use for floors, wet areas and outdoors. High-absorption BIII tiles are wall tiles.
Area ÷ tile size, rounded up to boxes
The number that actually protects you at the counter is the coverage printed on the box, not the tile count. Tiles per box varies between manufacturers for the same nominal size, so two boxes both labelled 600×600 can hold different quantities and cover different areas. Take your area, add the wastage, then divide by the box's stated coverage — that is the figure to order against.
The calculator works on the nominal tile size and ignores the grout joint, which makes it round slightly high — the safe direction. A 600 mm tile laid with a 2 mm joint occupies a 602 mm module, so ignoring the joint over-estimates by about 0.7%; a 300 mm tile with a 3 mm joint over-estimates by about 2%. Both sit well inside the wastage allowance, so no separate adjustment is needed.
- Area
- Floor or wall area—L × W in m²
- tile_area
- Per-tile area—tile L × W in m²
How to use this calculator
Enter the area, pick tile size and box count, set wastage.
Enter floor or wall area
Length × width in metres. For multi-room layouts, calculate each room separately.
Pick tile size
Common: 300×300, 600×600, 800×800, 1000×1000 mm. Larger tiles = fewer joints + faster laying but higher wastage on cuts.
Enter tiles per box
Check the box label — varies by tile size. 600×600 typically 4 per box. Calculator rounds up to whole boxes.
Set wastage
10% standard, 15-20% for diagonal layouts or rooms with many corners and cuts.
Common tile projects
Bathroom walls + floor
Calculate walls and floor separately. Different tile sizes are common (smaller on walls, larger on floor).
Living room floor
Most common project. Big-format tiles (800×800 or 1000×1000) for fewer joints; smaller (600×600) for easier handling.
Kitchen backsplash
Small mosaic or 200×200 tiles for visual interest. Higher waste % due to small cuts.
Outdoor patio / verandah
Anti-skid tiles, often 300×300 vitrified. Calculator works the same way.
Skirting along the walls
Skirting is sold by running metre or cut from full floor tiles. It is a separate quantity from the floor — measure the room perimeter, subtract door widths, and order it on top of the floor figure.
Common tiling estimate mistakes
Adding the wastage allowance to the box count instead of the tile count.
Apply wastage to the tiles first, then round up to whole boxes. Rounding first and then adding 10% to a box figure gives a different — usually short — answer.
Assuming every box of the same tile size holds the same number of tiles.
Read the coverage in square metres off the box and order against that. Tiles per box is a manufacturer choice, not a standard.
Using the standard 10% wastage for a diagonal or herringbone layout.
Angled layouts cut every perimeter tile and the offcuts are rarely reusable. Use 15-20% for diagonal and herringbone work.
Estimating a bathroom as one number instead of walls and floor separately.
Walls and floors usually take different tile sizes and different wastage. Run the calculator once for each and add the results.
Forgetting skirting, thresholds and step risers.
These are cut from full tiles and are easy to leave out of a floor-area figure. Measure the perimeter and any steps, and add them to the order.
Buying the exact quantity with no spares from the same batch.
Order 1-2 boxes over and keep them. A replacement bought two years later will be a different production batch and will not match.
Glossary
- Vitrified tile
- Highest-density ceramic tile — water-resistant, durable. Common for floors.
- Wastage
- Buffer % to account for cuts at edges, breakages during laying, and trim pieces.
- Batch number
- Manufacturing batch identifier on each box. Same batch = same colour shade.
- Box coverage
- The floor area one box tiles, printed on the box in square metres or square feet. This is the number to order against, since tiles per box varies by manufacturer.
- Rectified tile
- A tile ground to an exact size after firing, so it can be laid with a very narrow joint. Non-rectified tiles carry a wider size tolerance and need a wider joint.
- Water absorption group
- The IS 15622 / ISO 13006 class describing how much water a tile body absorbs — BIa (0.5% or less) through BIII (over 10%). Lower absorption means denser, harder and more suitable for floors and wet areas.
Frequently asked questions
How much wastage should I add for tiles?
Should I buy extra tiles even after the project?
How do I work out how many tiles I need for a room?
How many tiles come in one box?
Do larger tiles need more or less wastage?
References
- IS 15622:2017 — Pressed ceramic tiles: classification by water absorption group— Bureau of Indian Standards
- IS 15477 — Adhesives for use with ceramic tiles— Bureau of Indian Standards