The formula
How it works
Work out how many tiles you need for a floor or wall from the size of the area and the size of a tile, with a waste allowance for cuts and breakages. Add a price per tile to estimate the total cost.
FAQ
How much waste should I allow?
Around 10% is standard for a simple rectangular room. Add more — 15% or so — for diagonal layouts, patterned tiles, or rooms with lots of cuts around fixtures.
Why buy extra tiles?
Beyond covering cuts and breakages, keeping a few spare tiles from the same batch means you can replace a cracked one later with an exact colour match, since dye lots change over time.
Does this include grout lines?
No — the calculator treats each tile as its full width and height, so it does not subtract grout joints. For most tile sizes the joints are thin enough that the effect on the count is negligible, but very wide grout lines on small tiles can shave the total slightly.
How do I measure an L-shaped or irregular room?
Split the room into rectangles, work out the area of each separately, and add them together before dividing by the tile area — or simply enter the combined total area as the room length times a width of 1.
Should I increase the waste allowance for large-format tiles?
Large-format tiles are more expensive to break and harder to cut cleanly, so many installers still budget 10–15% even though fewer full tiles fit each row. It also protects against warped subfloors that cause more edge cuts.
How many tiles come in a box?
This varies by manufacturer and tile size and is not something this calculator can know, so check the box label or product page, then divide the number of tiles needed by that figure and round up to whole boxes.
Does switching between imperial and metric change the tile count?
No — the maths is unit-agnostic, so as long as the room and tile dimensions use matching units the result is the same either way, just displayed in feet/inches or metres/centimetres.
About the tile calculator
This calculator tells you how many tiles you need to cover a floor or wall, and roughly what they will cost. Tiling is unforgiving of a bad estimate: order too few and you risk a colour mismatch when you top up from a different batch, order too many and you have wasted money. By comparing the area you are covering with the size of each tile — and adding a sensible allowance for cuts — it takes the guesswork out of the order.
How to use it
Choose your units, then enter the length and width of the area to tile and the size of a single tile. Set a waste allowance for offcuts, and optionally a price per tile. The calculator shows the number of tiles to buy and the total cost. For example, a 10 ft by 10 ft floor tiled with 12-inch square tiles needs 100 tiles, plus about 10 more for a 10% waste allowance — so 110 in total. Round up to whole boxes when you order.
The formula
The number of tiles is the room area divided by the area of one tile, times a waste factor, rounded up: . The tile area is its width times its height, converted to the same units as the room. The ceiling brackets mean you always round up to a whole tile, because you cannot buy a fraction of one, and the waste factor adds a percentage for cuts and breakages.
Where it is used
Anyone tiling a bathroom, kitchen, floor or splashback uses this to order the right quantity. Tradespeople use it to quote jobs and buy materials, and DIYers use it to avoid a mid-project second trip to the shop. The same area-divided-by-unit maths applies to laminate planks, carpet tiles and paving slabs, making it a general tool for covering any surface with repeating pieces.