Free calculator
Tile calculator: tiles, boxes, grout and thinset
Enter the floor and any wall or shower areas, pick the tile size and layout, and get tiles and boxes with the right waste for the pattern, plus the grout and thinset to set them. A 10 × 12 floor in 12 × 24 tile on an offset lay takes about 9 boxes of 16 sq ft.
Areas to tile
Tile and setting materials
What to order
Tiles
68
134 sq ft incl. 12% waste
Boxes
9
At 16 sq ft per box
Grout
1 × 25 lb
6.6 lb sanded grout
Thinset
3 × 50 lb
½" × ½" square notch
120 sq ft of surface. Grout and thinset are typical figures — the coverage chart on the bag you buy takes precedence.
Quantities are half a bid. Send these to the free estimate builder to add labor, burden and markup, then hand the customer a proposal.
Every field takes arithmetic — type 24+18+12 and it adds. Nothing is sent anywhere; the math runs in your browser.
How the tile calculator works
Each area’s length times width is summed, waste for the layout is added, and the total is divided by the face area of one tile (length × width ÷ 144) and by the box coverage, both rounded up. Joints are ignored when counting tiles, which errs slightly toward buying one more — the right direction.
Waste by layout pattern
| Pattern | Typical waste | Why |
|---|---|---|
| Straight lay | 10% | Cuts at two walls only |
| Offset / running bond | 12% | Staggered rows start and end on cuts |
| Diagonal | 15% | Every perimeter tile is a triangle cut |
| Herringbone | 20% | Angled cuts on all four sides, more breakage |
Rooms with many corners, a toilet flange, a tub and a door jamb add cuts too — raise the waste rather than hoping.
Trowel size by tile size
| Longest side of tile | Typical notch | Coverage per 50-lb bag |
|---|---|---|
| Up to 8" | ¼" × ¼" square | ~95 sq ft |
| 8" to 15" | ¼" × ⅜" square | ~65 sq ft |
| Over 15" (large format) | ½" × ½" square | ~40–45 sq ft |
Typical figures; the thinset bag and the tile maker govern. Large-format tile is prone to lippage from warpage, so it usually calls for a large-and-heavy-tile mortar, back-buttering, a leveling system and an offset no greater than the manufacturer allows.
How the grout estimate works
Every tile carries one long joint and one short joint. Joint volume per square foot is (tile length + tile width) × joint width × tile thickness × tiles per square foot; the calculator multiplies that by about 0.06 lb of sanded grout per cubic inch and adds 10%. That is why the same floor needs much more grout in 3 × 6 subway than in 24 × 24 — the smaller tile has four times the joint.
Shower walls go over a waterproofed substrate — cement board with a liquid or sheet membrane, or a foam board system — and those are line items of their own. Price the substrate, membrane, setting and grouting in the estimate builder, or see the assemblies in the tile estimating software. Wall board around a tub surround comes from the drywall calculator, and the full method is in how to estimate a construction job.
Frequently asked questions
How much extra tile should I buy?
About 10% for a straight lay, 12% for an offset or running bond, 15% for diagonal and 20% for herringbone. Keep at least one unopened box after the job: dye lots change, and a matching replacement tile a few years later is often impossible to find.
How many boxes of tile do I need for 100 sq ft?
Add waste first, then divide by the box coverage. At 10% waste, 100 sq ft becomes 110 sq ft; with boxes that cover 15 sq ft, that is 7.3 boxes, so buy 8.
How much grout do I need?
It depends on joint width, tile thickness and tile size, because smaller tile means more joint per square foot. 12 × 12 tile, 3/8 inch thick with 1/8-inch joints, takes roughly 7 lb of sanded grout per 100 sq ft; widen the joint to 1/4 inch and it roughly doubles. Mosaics use far more.
What size trowel should I use for tile?
A 1/4 × 1/4-inch square notch is typical up to about 8-inch tile, 1/4 × 3/8 for tile up to about 15 inches, and 1/2 × 1/2 for large format. The notch is only a starting point: pull a tile and check coverage — industry standards typically call for about 80% in dry interior areas and 95% in wet areas. Follow the setting-material maker's instructions.
How many bags of thinset per 100 sq ft?
With a 1/4 × 3/8-inch notch a 50-lb bag typically covers about 65 sq ft, so 100 sq ft takes 2 bags. A 1/2-inch notch covers closer to 40–45 sq ft per bag — 3 bags — and back-buttering large-format tile adds more.
Quantities are half the bid.
BuiltSum prices them from trade assemblies, sends the proposal, and bills the job monthly — unlimited projects from $49/mo.
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