TheCalculatory
Construction & Home · Area & Materials Formula verified

Tile Calculator

Enter the room's length and width, the tile size, and a waste allowance for cuts — this works out how many tiles, and how many boxes, to buy.

Room
ft
ft
in
in
%
$
On-screen number pad
Tap to type into the highlighted field
Tiles needed
132
14 boxes
Room area
120
Boxes to buy
14

Step-by-step proofCheck by hand
This is a material-quantity estimate. The default 10% waste allowance covers most straight-lay jobs; a diagonal layout, a room with lots of corners, or a first-time DIY install can use noticeably more. Round up rather than down, and check your tile's actual box count against the one printed on the box.

How the tile count is calculated

Room length times width gives the floor area; one tile's length times width, converted from inches to square feet, gives its coverage. Dividing room area by tile area gives the raw tile count, which is then increased by the waste allowance for cuts and rounded up to a whole tile, since a cut piece still costs a full tile. Dividing by tiles-per-box, rounded up, gives the number of boxes to buy.

The formula

tiles = ⌈(room area × (1 + waste%)) ÷ tile area⌉  ·  boxes = ⌈tiles ÷ tiles per box⌉

Worked example

A 10 ft × 12 ft room (120 sq ft) with 12"×12" tiles (1 sq ft each) and 10% waste: 120 × 1.10 = 132 sq ft of tile needed, which at 1 sq ft per tile is exactly 132 tiles — 14 boxes at 10 tiles per box.

Frequently asked questions

Why is there a waste allowance?
Every tile job has cuts — at the edges of the room, around fixtures, or where a pattern doesn't line up evenly — and cut-off pieces usually can't be reused elsewhere. A waste allowance buys a few extra whole tiles up front so a mid-job run to the store isn't needed, and it's cheaper to have a couple of spares left over than to risk a discontinued batch not matching later.
Why round the tile count up instead of down?
Tiles are sold whole, and a partial tile still costs a full tile's worth of material once it's cut, so any fractional result is rounded up to the next whole tile — the same convention used for gallons of paint or bags of concrete.
Should I use a bigger waste allowance for a diagonal layout?
Yes — a diagonal (45°) layout creates more triangular cut pieces at the walls than a straight grid, so 15–20% waste is a more realistic allowance than the 10% default used for a straight lay. Adjust the waste field above if that's your plan.
Sources and method
  • Standard area-based material estimation with a waste allowance — general published construction-estimating practice.
Last reviewed: 20 Sep 2026 Sources last verified: 20 Sep 2026 Results use the assumptions explained on this page. Report an error How we check calculations

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