How Many Tiles Do I Need?

If you are asking how many tiles do i need, the honest answer is that no single number fits every room. The count depends on three things you can measure or choose: the size of the surface, the size of one tile, and the layout you intend to lay. Get those three right and the arithmetic is simple. Get any one of them wrong and you will either run short on the last row or store spare boxes for years. This guide works through the method step by step, with a table for the common sizes and a full worked example. If you would rather skip the arithmetic, our tile calculator does the same sums instantly, including the grout gap and the waste for your layout.

The direct answer

Divide the area you are tiling by the area one tile covers, then add a waste allowance for cuts and breakages, and round up. That is the whole method. A rectangular floor is length times width. One tile is its length times its width, converted into the same units. So a room of 120 square feet tiled with a tile that covers 2 square feet needs 120 divided by 2, which is 60 tiles before waste. Nothing more complicated is hiding underneath, and every professional estimate follows this same chain.

The waste allowance depends on the layout. Add 10% for a straight grid, where most cuts are simple and many offcuts can be reused. Add 15% for a diagonal layout, where every edge is an angled cut and the offcuts rarely fit anywhere else. Add 20% for herringbone and other complex patterns, where angled cuts come in pairs and a single mistake can waste a whole tile. The grout gap changes the count only slightly. Each laid tile effectively covers its own area plus one grout joint, so wider gaps cover marginally more area per tile and you need marginally fewer tiles. The effect is small, but it is real, and the calculator includes it rather than ignoring it.

How many tiles per 100 square feet?

The table below gives the net count for 100 square feet, before waste and before the grout gap, for the sizes people buy most often. Use it for a quick sense of scale, then add your layout waste on top. A small tile is not cheaper to lay just because it is small: notice how quickly the count climbs as the tile gets smaller, and how much grout and handling that implies.

Tile size	Tiles needed per 100 sq ft (before waste)
12×12 in	100
12×24 in	50
24×24 in	25
6×24 in plank	100
4×4 in	900

You can check any row by hand. A 24×24 inch tile covers 4 square feet, so 100 divided by 4 is 25 tiles. A 12×24 inch tile covers 2 square feet, so the same area needs 50. A 4×4 inch tile covers only a ninth of a square foot, which is why the count jumps to 900. Always round a fractional result up, because you cannot buy or lay part of a tile. For a room that is not exactly 100 square feet, scale the figure in proportion, or run your own measurements through the tile calculator and let it handle the rounding, the gap and the waste in one go.

Worked example: a 10 × 12 ft bathroom floor

Take a bathroom floor that measures 10 feet by 12 feet, tiled with 12×24 inch tiles in a straight layout. Work through it in the same order a tiler would. Step one is the area: 10 times 12 is 120 square feet. Step two is one tile: a 12×24 inch tile is 288 square inches, which is exactly 2 square feet. Step three is the net count: 120 divided by 2 is 60 tiles. Step four is waste: a straight layout needs 10%, and 60 plus 10% is 66 tiles. So the order quantity for the floor itself is 66 tiles, before you think about boxes or spares.

Step five is boxes, and this is where people most often go wrong. Tiles are sold by the box, and boxes vary by maker. One brand may pack enough 12×24 tiles to cover 12 square feet, another may cover 16, and a third may use a different count again. So divide your tile total, or the area with waste added, by the coverage printed on the box you are actually buying, and round up to whole boxes. In area terms this bathroom needs 132 square feet of tile once waste is included. Never assume a box covers a neat, standard amount, and never copy a box count from a different product, even one that looks identical on the shelf.

Walls and floors are measured differently

Floors: measure the whole room

On a floor, measure the full length and the full width and subtract nothing. Tiles normally run under appliances, under a freestanding bath where the design calls for it, and into the bottom of cupboards. The space a washing machine or a vanity unit stands on is still tiled underneath in most installations, and leaving it out saves very little while creating an awkward edge if you ever move things around. For an irregular floor, split the shape into rectangles, work out each one, and add them together.

Walls: measure each surface, then subtract openings

Walls are the opposite. Measure each surface separately and add the results. A splashback is its own run, measured by its length and height. Each shower wall is its own surface, and the shower floor is another one again. Then, on walls only, subtract the area of windows and doors that will not be tiled, because a tile count that includes a window is a count you will pay for and not use. Keep each surface written down separately until the end, so you can see where the total came from and adjust one wall without redoing the whole job. If your project is a floor and you work in metric as well as imperial, our companion guide, Tile Calculator for Floors — Square Feet and m², works the same method in both unit systems.

The dye-lot warning: buy the whole job in one order

Tile colour is set during firing, and it varies between production batches, sometimes called dye lots or shades. Two boxes with the same product name, bought months apart, can differ enough that the join shows clearly once they are laid side by side, especially in plain colours and in bright light. For that reason, buy the whole job, plus your waste, plus one spare box, in a single order from the same production batch. Check that the batch or lot number printed on the boxes matches before you accept delivery, and keep the spare box after the job is finished. That spare box is your insurance. If a tile cracks in five years and the line has been discontinued, a matching replacement from the original batch is the difference between an invisible repair and a floor that announces the repair forever.

Before you order: a short checklist

• Measure each surface twice, and round measurements up rather than down.
• Work out the net count from the area and one tile, in the same units.
• Add waste for your layout: 10% straight, 15% diagonal, 20% herringbone.
• Convert tiles to boxes using the coverage printed on the actual box.
• Add one spare box, and order everything in one go from the same batch.

Run that checklist once and most tile shortages disappear, because most shortages are measuring or rounding mistakes rather than bad luck. When you are ready, check your final numbers with the tile calculator, compare its result with your hand figure, and only order when the two agree. If they do not agree, the difference is usually the grout gap or a waste percentage left on the wrong setting, and finding it now is far cheaper than finding it with half a floor laid.

Frequently asked questions