OnSumoTools

Tile Coverage Calculator

Estimate tiles and boxes for floors, walls, and backsplashes with grout, layout waste, and multi-room totals.

Units

Areas to tile

Tile specs

Tiles needed

108

Boxes needed

11

Estimated cost

$495

Total area: 100.0 sq ft. Includes 10% for cuts and breakage.

You will have 2 tiles left over in the boxes you buy. Keep leftover tiles stored flat in a dry place for future repairs.

Per-section breakdown

SectionAreaTiles (with waste)
Main floor100.0 sq ft108

Tile counts are estimates. Always confirm pattern and site cuts with your installer before ordering.

How does the Tile Coverage Calculator work step by step?

Add one or more room sections, pick tile size and grout width, then choose a layout pattern. The calculator includes waste for cuts and breakage and rounds up to full boxes.

What does a typical Tile Coverage Calculator result look like?

You are tiling a 10 by 12 ft kitchen backsplash plus a 4 by 3 ft nook. Enter two sections, set 3 by 6 inch subway tile, and buy the box count shown with 10% waste.

Frequently asked questions

  • Why does diagonal layout need more tiles?

    When tiles are set at a 45-degree angle, every wall edge and obstacle creates angled cuts that generate more waste than a straight grid layout would. Corner pieces often lose half their area or more. This calculator automatically applies a minimum 15 percent waste factor when diagonal layout is selected to account for those additional cut pieces at room perimeters.

  • Should I buy extra tiles?

    Order 10 to 15 percent more than the bare calculated count. Tiles within the same product line can vary slightly in shade between production runs. If you need to repair a cracked tile years later and the line has been discontinued, having extras on hand from the original lot will save you from a difficult color-matching problem.

  • How do grout joints affect tile count?

    Grout joints add a small amount of space between each tile, which slightly increases the effective footprint of every piece in the layout. A 12-inch tile with a 3 mm grout joint occupies just over one square foot of floor area. For larger rooms with wider joints this effect is small but still worth including in an accurate tile count.

  • Can I add more than one room?

    Yes. Add one section row for each room or distinct area in your project, each with its own dimensions and layout type. The calculator sums all section areas into a single combined total, then produces one tile count and box quantity for the full order so you can purchase everything in a single trip or shipment.

Count tiles before you shop

Tile is sold in boxes, and boxes rarely match your room exactly. This calculator turns your room sizes into a tile count, boxes to buy and the number left over.

Add a section for each area, like a bathroom floor or a kitchen backsplash. Enter the tile size and the grout joint width, and the tool does the rest.

Why grout joints matter

Each tile takes up its own size plus half a joint on every side. On small tiles, like mosaics, the joints eat up a real share of the area. On big tiles, the effect is tiny. The tool counts the grout footprint so your numbers aren't off.

Layout and waste

Cuts at the edges, bad tiles and mistakes all need a spare. Plan for 10 percent on a simple straight layout. A diagonal pattern wastes more, so 15 percent is safer, because many tiles get cut at an angle and the offcuts are often unusable.

Set the layout in the tool and it applies a matching waste rate. It also shows how many tiles you'll have left, which is handy to keep for future repairs.

  • Buy all boxes from the same lot so the color matches
  • Open a few boxes and mix tiles while laying, to blend shade differences
  • Keep a box or two of spares, since styles get discontinued

A quick example

A bathroom floor is 8 by 10 feet, which is 80 square feet. You pick 12 by 12 inch tiles with a 1/8 inch joint. Each tile covers a hair over one square foot including its joint, so you need around 78 whole tiles, and a bit more once the edges are cut.

Add 10 percent for waste and you're at about 86 tiles. If a box holds 10, you buy 9 boxes and have 4 spare tiles. Those spares are worth keeping in the garage.

Before you start laying

Dry-lay a row without adhesive. It shows where the cuts will land and whether you'll end up with a thin sliver at one wall. Shifting the start line by half a tile often fixes that.

The floor needs to be flat. A big tile on a wavy surface will rock and crack. Check with a long straightedge and fix low spots with leveling compound.

Last, use the right adhesive for the tile and the room. Wet areas need a waterproof layer under the tile, not just on top of it. Grout lines are not waterproof on their own.

Cost check

Enter the price per box or per tile and you'll see the total. Don't forget thin-set, grout, spacers and sealer. They add up.

Everything stays on your device.

Measuring the room properly

Measure length and width in two or three places, since walls are rarely straight. Use the largest figure. For a room with an alcove, split it into rectangles, work out each and add the areas.

Take off fixed items only if they're large and stay put, like a built-in tub. Don't subtract small things, since cuts around them waste tiles anyway.

Write the numbers down in one unit. Mixing meters and feet is the easiest way to buy the wrong amount.

Boxes, batches and spares

Tiles are sold by the box, and a box covers a set area. Round up to whole boxes, never down. Buy everything from the same batch, since color and size can differ slightly between production runs, and a second order months later may not match.

Keep one or two spare tiles after the job. If something cracks in five years, you'll be glad to have them.

Large format tiles and diagonal patterns need more waste than a straight grid. Ten percent is a decent starting point for simple layouts and fifteen or more for complex ones.