How many tiles do I need for a bathroom?

It depends entirely on your bathroom's floor and/or wall area. Measure the length and width of each surface you're tiling, multiply for the area, then use this calculator with your chosen tile size and grout joint to get an exact tile and box count — a typical small bathroom floor (around 4-6 m²) needs roughly 45-70 tiles at 300 x 300mm including a 10% waste allowance.

How much extra tile should I order for waste?

A standard allowance is 10% for a straightforward straight-grid layout in a rectangular room. Increase this to 15-20% for diagonal or herringbone patterns, complex room shapes with many corners, or pattern-matched tile (like wood-look plank tile) where pieces need to be selected carefully to avoid repetition.

Does grout joint width really affect how many tiles I need?

Yes — a wider grout joint slightly increases the effective footprint each tile occupies, which reduces how many tiles fit in a given area. The effect is small per tile but adds up: for smaller tiles or larger jobs, a joint that's a couple of millimetres wider than expected can shift your final tile count by several tiles or more.

Why does my box count seem to waste extra tiles?

Boxes are sold as fixed units — if you need 144 tiles and a box holds 10, you need 15 boxes (150 tiles), not 14.4. That "extra" 6 tiles is normal and intentional: keep them as spares for future repairs rather than treating them as wasted material.

Should I add more waste for a diagonal or herringbone layout?

Yes. Diagonal and herringbone patterns require far more angled cuts along the edges of the room than a straight grid layout, so they typically need 15% or more waste allowance compared to the standard 10% for straight lays. This calculator automatically suggests a higher default when you select a diagonal layout pattern.

Is limestone or traditional stone flooring common instead of tile in Malta?

Traditional Maltese homes often used local limestone (Franka or Qawwi) for flooring, but modern renovations overwhelmingly use imported ceramic and porcelain tile in standard metric sizes — this calculator applies to both, since the tile-count math is identical regardless of the material's origin.

Tile Calculator — How Many Tiles Do I Need?

How Many Tiles Do I Need? Tile Calculator Guide

Before you order a single box of tile, you need one number: how many tiles will actually cover your floor, wall, or shower surround. Get it wrong on the low side and you're back at the store mid-job hoping the batch number still matches; get it wrong on the high side and you've overpaid for tile sitting in a garage. This calculator solves that by combining your area, your tile size, your grout joint width, and a waste allowance into one reliable tile count and box count.

The tricky part most quick mental-math approaches miss is the grout joint. A 300 x 300mm tile doesn't actually occupy 300 x 300mm of your floor once it's installed — the joint width around it eats into the coverage, so the real 'footprint' of each tile is slightly larger than its face size. Skip that adjustment and you'll consistently under-order, especially on larger jobs where the error compounds across hundreds of tiles.

This tool also goes further than a bare area-divided-by-tile-area formula: it accounts for your layout pattern (a straight grid lay wastes far less than a diagonal or herringbone pattern, which forces more edge cuts), converts the result into whole boxes based on your supplier's tiles-per-box count, and gives you a real material cost estimate so you know what to budget before you're standing in the aisle.

Whether you're tiling a bathroom floor, a kitchen backsplash, or a full shower enclosure, the underlying math is identical — only the area, tile size, and waste allowance change. Enter your numbers below and you'll get a tile count, box count, and cost estimate in seconds.

How to use the tile calculator

Enter the length and width of the area you plan to tile (a room, wall, or shower surround) — the calculator multiplies these into a total area.
Enter your tile size (length x width). Use one of the common size presets — 300 x 300mm, 600 x 600mm, 450 x 900mm, 12 x 12in, or 18 x 18in — or type in a custom size if your tile is a different format.
Enter the grout gap (joint width) you plan to use between tiles. A typical joint is 2-3mm for rectified porcelain or 3-5mm for standard ceramic; wider joints for natural stone or rustic-look tile.
Choose your layout pattern — straight (grid) or diagonal/herringbone. The calculator applies a higher default waste allowance for diagonal layouts since they generate more angled cuts.
Adjust the waste percentage if needed (10% is standard for straight lays, 15% or more for diagonal, complex layouts, or rooms with lots of corners/fixtures).
Enter how many tiles come in a box (check your supplier listing) and the price per box, to get an instant materials cost estimate alongside your tile count.

The tile calculation formula, explained

The core formula is: tiles needed = area to tile / effective area of one tile. The 'effective area' is not the raw tile face size — it's the tile's length and width each increased by the grout joint width, since that joint is the space the tile plus its share of the surrounding grout actually consumes on the wall or floor.

In formula terms: effective tile area = (tile length + joint width) x (tile width + joint width). Divide your total area by that number to get the raw tile count, then add your waste percentage, then round up to the next whole tile — you can only buy whole tiles, so any fraction always rounds up rather than down.

Once you have the tile count, box count is simply: tiles needed / tiles per box, rounded up. Even if you need one tile more than a full box's worth, you have to buy the whole extra box — that's why box count almost always looks like it 'wastes' a few tiles, which is normal and expected.

Worked example: a bathroom floor measuring 4m x 3m = 12 m² total area.
Tile size: 300 x 300mm (0.3m x 0.3m) with a 3mm (0.003m) grout joint.
Effective tile area = (0.3 + 0.003) x (0.3 + 0.003) = 0.303 x 0.303 = 0.0918 m².
Raw tile count = 12 / 0.0918 = 130.7 tiles.
Add 10% waste for a straight lay: 130.7 x 1.10 = 143.8, rounded up to 144 tiles.
If the tile comes 10 to a box: 144 / 10 = 14.4, rounded up to 15 boxes.
At a typical box price, that gives you a full materials cost estimate before you ever visit the store.

Common tile sizes and typical joint widths

300 x 300 mm — a standard small-to-mid floor tile size across Europe and Australia, common in bathrooms and utility rooms.
600 x 600 mm — the most common large-format floor tile today, popular for open-plan living spaces and modern kitchens.
450 x 900 mm — a common large-format rectangular ("plank-style") floor and wall tile.
12 x 12 in (~305 x 305 mm) and 18 x 18 in (~457 x 457 mm) — the standard US/Canada imperial equivalents to the metric sizes above.
Grout joint width: 1.5-3mm for rectified (precision-cut) porcelain tile; 3-5mm for standard ceramic and non-rectified tile; 6mm+ for rustic, handmade, or natural stone tile where edges are less uniform.
Reference: Tile Council of North America (TCNA), ANSI A137.1 — American National Standard Specifications for Ceramic Tile; EN 14411 — the European ceramic tile product standard.

Pro tips and common mistakes

Always buy tile from the same production batch (same "lot" or "shade" number) — dye lots vary slightly between production runs, and mismatched batches show up as a visible colour or shade difference once installed.

Worked example at Maltese prices: a 12 m² bathroom floor using 300 x 300mm tiles with a 3mm grout joint and 10% waste comes to roughly 144 tiles, or 15 boxes at 10 tiles per box. At a typical Maltese price of around €30 per box, budget approximately €450 for tile alone, before adhesive, grout and installer labour.

Diagonal and herringbone layouts waste significantly more tile than a straight grid lay — budget 15-20% waste instead of the standard 10%, since almost every edge tile needs an angled cut.
Pattern-matched tile (wood-look plank tile, veined stone-look tile) needs extra waste allowance beyond the standard cut-loss figure, since you may need to skip pieces to keep the pattern looking natural rather than repetitive.
Order a little extra (beyond your waste allowance) and keep a few spare tiles after the job — future repairs are far easier with tile from the original batch than trying to colour-match years later.
Rooms with lots of corners, niches, or fixtures (toilets, vanities, shower benches) generate more cut pieces than a simple rectangular room — nudge your waste percentage up if your layout is complex.
Double-check your area measurement before ordering: measure twice, and account for any recesses, alcoves, or door thresholds that add to (or subtract from) the simple length x width figure.
Don't confuse the tile's box coverage area (often printed in m² or sq ft per box) with the number of tiles per box — always confirm both figures from your supplier since box sizes vary between manufacturers.