Tile & Flooring Calculator
Work out how many boxes of tile or flooring to buy, how many tiles that is, and roughly how much grout the joints need.
Vroxify: vroxify.com
Tile and flooring calculator
Results appear here as you type.
How the calculator works
Tile, laminate, vinyl plank and engineered wood are all sold by the box, and every box lists the area it covers. So the main calculation is short: room area, plus a waste allowance for cuts and breakage, divided by box coverage, rounded up to whole boxes. If you also enter a tile size, the calculator counts individual tiles (allowing for grout joints) and estimates how much grout the joints hold.
The waste allowance does most of the work, and it depends on the layout. A straight grid wastes the least because cut pieces from one side often fit the other. Diagonal and herringbone layouts cut almost every edge piece at an angle, so more ends up in the bin. The defaults (10% straight or offset, 15% diagonal, 20% herringbone) are common trade rules of thumb, not a standard, so raise them for small or awkward rooms and large-format tiles.
The formulas
Area to buy = (length × width + extra) × (1 + waste %) Boxes = area to buy ÷ coverage per box (round up) Tiles = area to buy ÷ ((tile L + joint) × (tile W + joint)) Grout volume = area × joint width × tile thickness × (L + W) ÷ (L × W)
The grout formula is plain geometry: each tile “owns” one joint along its length and one along its width, each as deep as the tile is thick. The result is the volume of the joints with nothing added for waste. Grout makers publish coverage charts for their own products, so compare this volume with the chart on your bag and buy accordingly.
Worked examples
A 10 × 12 ft kitchen in 12 × 12 in tile
Area 120 ft², plus 10% for a straight layout, gives 132 ft². With boxes of 15 ft²: 132 ÷ 15 = 8.8, so 9 boxes. Counting tiles with ⅛ in joints, each tile plus joint takes 12.125 × 12.125 in, so 132 ft² needs 130 tiles. The joints for ⅜ in thick tile hold about 135 in³ (roughly 2.3 US quarts) of grout before waste.
A 3 × 3.6 m hallway in herringbone vinyl plank (metric)
Area 10.8 m², plus 20% for herringbone, gives 12.96 m². With boxes of 1.4 m²: 12.96 ÷ 1.4 = 9.26, so 10 boxes. A straight layout of the same floor would need 11.9 m², or 9 boxes. The pattern costs one extra box here.
Tips for buying tile and flooring
- Buy from one batch or lot. Shade and size can vary between production runs. Check that the lot number is the same on every box.
- Keep spares. A few leftover tiles or planks make a future repair invisible; a discontinued colour is hard to match later.
- Measure out-of-square rooms at both ends and use the larger number, then add any closets and alcoves in the Extra area field.
- Follow the product’s instructions for underlayment, acclimation and expansion gaps. They differ between laminate, vinyl, wood and tile, and they can affect the warranty.
- Large-format and patterned tiles waste more. If cutting or pattern matching is involved, raise the waste allowance.
Frequently asked questions
How much extra tile should I buy?
A common rule of thumb is about 10% for straight or offset layouts, about 15% for diagonal layouts, and about 20% for herringbone. Small or irregular rooms and large tiles may need more.
How many boxes of flooring do I need for 120 ft²?
With 10% waste you need 132 ft². Divide by the coverage printed on the box and round up. With 15 ft² boxes that is 9 boxes.
How do I calculate how much grout I need?
Joint volume = area × joint width × tile thickness × (tile length + tile width) ÷ (tile length × tile width). Then compare it with the coverage chart on your grout bag, which accounts for that product’s density.
Should I count closets and areas under appliances?
Count any area that will be covered. Many people skip the space under fixed cabinets, but include closets, alcoves and doorways in the Extra area field.
Does this work for wall tile?
Yes. Enter the wall’s width and height as length and width, and subtract windows or a bathtub by entering only the tiled area.