Tile Calculator
Enter the area and tile size. The calculator accounts for grout joints and adds waste for your pattern. It also estimates grout and thinset, so you buy everything in one trip.
- Tested formulas
- Feet or metric
- Printable shopping list
2 What to buy
Updates as you type| Tiles without waste | 39.4 |
|---|---|
| Waste allowance | 12% |
| Tile area to buy | 90 sq ft |
| Grout (sanded or unsanded) | 4.3 lb · 1.9 kg → 1 × 25 lb bag |
| Thinset mortar | 2 × 50 lb bags (≈50 sq ft per bag) |
Shopping list
Quick answer
A 10 × 8 ft floor with 12 × 24 inch tile in an offset pattern needs 45 tiles including 12% extra, or 6 boxes at 15.5 sq ft per box. Add 10% for a straight grid, 15% for diagonal and 20% for herringbone.
Tiles needed for common areas
| Area | 12"×12" | 12"×24" | 18"×18" | 24"×24" |
|---|---|---|---|---|
| 5 × 5 ft (25 sq ft) | 27 tiles | 14 tiles | 13 tiles | 7 tiles |
| 5 × 8 ft (40 sq ft) | 44 tiles | 22 tiles | 20 tiles | 11 tiles |
| 8 × 10 ft (80 sq ft) | 87 tiles | 44 tiles | 39 tiles | 22 tiles |
| 10 × 10 ft (100 sq ft) | 108 tiles | 55 tiles | 49 tiles | 28 tiles |
| 10 × 15 ft (150 sq ft) | 162 tiles | 82 tiles | 73 tiles | 41 tiles |
| 15 × 20 ft (300 sq ft) | 324 tiles | 163 tiles | 145 tiles | 82 tiles |
Straight layout with 10% extra, ⅛" joints. Use the calculator above for your exact size.
How to calculate tiles
- Measure the area (length × width). Split L-shaped rooms into rectangles.
- Work out how much area one tile covers including one grout joint.
- Divide, then add waste for cuts: 10% for a straight grid, 12% for offset, 15% for diagonal and 20% for herringbone.
- Divide the tile area to buy by the coverage on the box, and round up.
Worked example: 10 × 8 ft bathroom, 12×24" tile, offset
- Area: 80 sq ft. Each tile with a ⅛" joint covers 2.03 sq ft → 39.4 tiles
- +12% waste = 45 tiles = 90 sq ft → 6 boxes at 15.5 sq ft/box
- Grout ≈ 4.3 lb (1 bag), thinset 2 × 50 lb bags
Why buy extra tile?
Beyond cuts and breakage, keep a few spare tiles after the job. Tile lines are discontinued, and colors vary between production lots. Years later, a cracked tile is easy to replace if you have spares from the same lot, and nearly impossible if you don't. Always check that every box has the same lot or shade number.
Large-format tile tips
For tiles with any side 15" or longer, use a large-format (LHT) mortar and a ½" notch trowel. Back-butter each tile, and stagger offset patterns by no more than ⅓ to avoid lippage from the slight bow in long tiles. That's also why the calculator assumes thinset covers about 50 sq ft per bag for large tiles versus about 95 for smaller ones.
Frequently asked questions
How much extra tile should I buy?
10% for a straight layout, 12% for offset/brick, 15% for diagonal and 20% for herringbone or rooms with many corners. Add a few more tiles to keep as spares.
How many 12×24 tiles do I need for 100 sq ft?
Each 12×24 tile covers 2 sq ft, so 50 tiles before waste, and about 56 with a 12% offset-pattern allowance.
How much grout do I need?
It depends on tile size, thickness and joint width. Small tiles with wide joints need far more. A 100 sq ft floor of 12×24 tile with ⅛" joints needs only about 5 lb, while 4×4 tile with ¼" joints can need 25 lb or more.
Last reviewed 2026-10-21. See how we calculate for our sources and assumptions.