How to Calculate Tile Quantity
Measure each surface, convert to the same units, then multiply length × width. Add areas together if you have more than one room or a shower with a floor plus walls. Divide by the face area of one tile, then multiply by (1 + waste). Always round the tile count up.
Worked example: an 8 ft 7 in × 5 ft 2 in bathroom floor is 103 in × 62 in = 6,386 sq in = 44.35 sq ft. With 12"×12" tile and a straight layout (10% waste): 44.35 × 1.10 ≈ 48.8 sq ft ≈ 49 tiles. Enter about 8.583 × 5.167 ft in the calculator to match that bathroom floor.
Pattern comparison: a straight layout on a 44 sq ft room needs about 4 fewer tiles than the same room in herringbone, because herringbone defaults to 17.5% waste instead of 10%.
Grout, Mortar, and Adhesive — What Else You'll Need
Grout coverage depends on joint width and tile size. A 12"×12" tile with a 1/8" joint is the baseline here: about 1 lb of grout per 8–10 sq ft (this tool uses 9). Wider joints and smaller tiles use more grout per square foot; large-format tile uses less. Thinset/mortar is estimated at about 45 sq ft per 50 lb bag on a flat substrate, or 35 sq ft per bag once tile face area is 16"×16" or larger (large-format trowels cover less). Confirm bag coverage on the product you buy.
Trim and Edge Pieces
If an edge is exposed — a step, a tub deck, or an open wall end — divide that linear length by the length of one trim or bullnose piece and round up. Worked example: a 10 ft exposed edge using 6" bullnose trim is 120 in ÷ 6 in = 20 pieces. Enter 10 ft of exposed edge and leave trim at 6" to see that count in the result box.
Ceiling Tile Calculator (Drop Ceiling)
Drop ceilings are a different shopping list: acoustic tiles plus a metal grid. Divide ceiling area by 2×2 ft (4 sq ft) or 2×4 ft (8 sq ft) and add about 5% waste — grid systems need far less cutting than ceramic. Main runners typically run at 4 ft intervals; 2×2 layouts also need 2 ft cross tees, while 2×4 layouts usually only need 4 ft tees. Wall angle follows the room perimeter. Use Ceiling Tile mode for those component counts, then check Armstrong, USG, or CGC layout charts before you order.
Carpet Tile Calculator
Carpet tile is modular: divide room area by one tile (18"×18" = 2.25 sq ft, or 24"×24" = 4 sq ft) and add about 5% waste. Cuts are cleaner than ceramic, so you need less extra than hard tile. If your carton lists tiles per box, fill that optional field to get a box count. For broadloom roll carpet (sq yd / stairs), use the Carpet Calculator instead.
Tile Quantity by Layout Pattern
| Layout | Typical waste | Notes |
|---|---|---|
| Straight / grid | 10% | Fewest cuts on a rectangular room |
| Brick / subway offset | 10% | Same waste as straight; more edge cuts on walls |
| Diagonal | 15% | Every perimeter tile is a cut |
| Herringbone | 15–20% | This tool defaults to 17.5% |
Mosaic sheets and natural stone can need a couple of extra points on top of the pattern default because breakage and culling run higher. Large-format tile (16"×16"+) uses a similar percentage waste, but each miscut costs more.
Frequently Asked Questions
How do I calculate how many tiles I need?
Divide your room's total area by the area of one tile, then add a waste factor of 10% for a simple layout or 15–20% for diagonal or herringbone patterns. The calculator above does this instantly once you enter your room and tile dimensions.
How much extra tile should I buy for waste?
Buy 10% extra for a straight or brick-pattern layout, and 15–20% extra for diagonal, herringbone, or rooms with lots of corners and cuts. Small-format tile and mosaic sheets generally need less extra than large-format tile, which breaks more expensively per piece.
How many boxes of tile do I need?
Divide your total tile count (including waste) by the number of tiles per box, then round up to the next full box — partial boxes aren't sold. Check your specific tile's box coverage, since it varies by manufacturer and tile size.
How do I calculate tile for a shower or bathroom?
Measure floor and wall areas separately, since they're often different tile sizes or materials, then calculate each the same way: area ÷ tile size, plus waste. Use the Shower/Bathroom mode above to handle both in one calculation.
How much grout do I need for tile?
Grout coverage depends on tile size and joint width — larger tiles with narrow joints need far less grout per square foot than small mosaic tile with wide joints. A 12"×12" tile with a 1/8" joint typically needs about 1 lb of grout per 8–10 sq ft.
How much thinset or mortar do I need for tile?
A standard notched trowel typically covers 40–50 sq ft per 50 lb bag on a flat substrate. Larger-format tile needs a bigger-notch trowel, which covers less area per bag — check your tile manufacturer's recommended trowel size.
How many drop ceiling tiles do I need?
Divide your ceiling's area by the tile size (usually 2×2 or 2×4 ft), adding only about 5% waste since grid ceilings need minimal cutting. You'll also need main runners, cross tees, and wall angle trim — see the Ceiling Tile mode above for exact grid-component counts.
How many carpet tiles do I need?
Divide your room's area by one carpet tile's size and add about 5% waste — carpet tile cuts more cleanly than hard tile, so it needs less extra than ceramic or porcelain.
How many trim or bullnose pieces do I need?
Divide the total linear length of exposed tile edges by the length of one trim piece. A 10 ft edge using 6" bullnose pieces needs 20 pieces (120 inches ÷ 6 inches).
Does tile size affect how much waste I should buy?
Yes. Larger tiles (16"×16" and up) break more expensively per piece if miscut, but generally need a similar percentage waste factor to smaller tile for the same layout pattern — the dollar cost of a mistake is what changes, not the percentage.
Can I use this instead of my retailer's calculator (Home Depot, Lowe's, Floor & Decor)?
Yes, as an independent, brand-agnostic estimate to sanity-check any retailer's tool or a contractor's quote. Retailer calculators are tuned to that store's specific box sizes and product line, so always confirm final order quantities against the exact product you're buying.
How do I calculate tile in square meters instead of square feet?
Switch to Metric mode above to enter room and tile dimensions in meters/centimeters and get results in square meters — the same formula (area ÷ tile size × waste factor) applies regardless of unit system.
Get free quotes from local tile installers
Box coverage, grout color, and substrate prep swing the bid. Get two or three written quotes before you order.