Flooring Calculator
Work out how much tile, laminate, vinyl plank, hardwood or carpet you need for any room. Get square footage with the right waste for your layout, boxes to buy and cost. The list also covers underlayment, thinset, grout, trim and carpet pad.
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Flooring needed = room length × width + extra areas, plus 10% waste (15% diagonal, 20% herringbone). A 15 × 12 ft room is 180 sq ft, so buy 198 sq ft. That is 9 boxes of 22 sq ft laminate, or 99 tiles of 12 × 24 in.
How to use this flooring calculator
- Pick the flooring type: tile, laminate or vinyl plank, hardwood, or carpet.
- Measure the room wall to wall at the widest points. Add closets, alcoves and hallways in the extra area field.
- Choose your layout. It sets the waste: diagonal and herringbone patterns cut far more material.
- Enter coverage per box from the label (or tile size), and your price.
- Read the order: boxes, tiles or square yards, cost, and the extra materials for that floor type.
How to measure a room for flooring
- Rectangular roomsLength × width, measured into door openings and under where the trim will go.
- L-shaped and irregular roomsSplit into rectangles, work out each one and add them up. Use the extra area field for the second rectangle.
- Closets and hallwaysAdd them separately. They are small but full of cuts.
- Do not subtractKitchen islands or built-ins. Measure the open floor only if the cabinets are already installed.
Measure in two or three places along each wall, because few rooms are perfectly square, and use the largest figure.
How much waste to add by layout
| Layout | Waste | 180 sq ft room becomes |
|---|---|---|
| Large open room, straight | 5–7% | 189–193 sq ft |
| Standard straight lay | 10% | 198 sq ft |
| Diagonal or brick offset | 15% | 207 sq ft |
| Herringbone, chevron | 20% | 216 sq ft |
Buy whole boxes from the same production lot so the color and shade match, and keep one spare box for future repairs.
Tile: how many tiles, and how much thinset and grout
| Tile size | Sq ft per tile | Tiles per 100 sq ft (+10%) |
|---|---|---|
| 3 × 6 in subway | 0.125 | 880 |
| 6 × 6 in | 0.25 | 440 |
| 12 × 12 in | 1.00 | 110 |
| 6 × 24 in plank | 1.00 | 110 |
| 12 × 24 in | 2.00 | 55 |
| 24 × 24 in | 4.00 | 28 |
A 50 lb bag of thinset covers roughly 80–95 sq ft with a 1/4 × 1/4 in trowel, but only about 40–50 sq ft with the 1/2 in notch that large-format tile needs. Grout depends on joint width and tile size, and small tiles use far more. See the tile flooring calculator and tile grout calculator for exact figures.
Laminate, vinyl plank and hardwood
| Floor | Typical box coverage | Underlayment | Install |
|---|---|---|---|
| Laminate | 18–25 sq ft | Foam or cork, unless attached | Floating, 1/4–3/8 in expansion gap |
| Luxury vinyl plank | 20–30 sq ft | Often attached pad | Floating or glue-down |
| Engineered hardwood | 20–30 sq ft | Per manufacturer | Float, glue or nail |
| Solid hardwood | 18–25 sq ft | Felt or synthetic paper | Nailed over wood subfloor |
Don’t forget baseboard or quarter round to cover the expansion gap. That is about the room perimeter plus 10%, in 8 ft lengths. See the laminate and hardwood calculator and baseboard trim calculator.
Carpet: square yards and roll width
Carpet is priced per square yard (sq ft ÷ 9) but cut from 12 ft wide rolls, sometimes 15 ft. A 15 × 12 ft room fits one 12 ft strip with no seam and needs about 21 sq yd with trim. A 15 × 14 ft room needs two strips and a seam, and buys noticeably more carpet than its floor area suggests. Pad is bought to the floor area plus about 5%.
Worked example
- Room 15 × 12 ft
- 180 sq ft
- Straight lay, +10% waste
- 198 sq ft
- Laminate, 22 sq ft per box
- 9 boxes (198 sq ft)
- Perimeter 54 ft + 10%
- 8 lengths of quarter round
- Underlayment (100 sq ft rolls)
- 2 rolls
All 8 interior finishes calculators
Calculators for every interior finish: floors, walls, paint, insulation and trim.
Frequently asked questions
How do I calculate how much flooring I need?
Length × width plus extra areas, then add 10% (straight), 15% (diagonal) or 20% (herringbone). Divide by box coverage and round up.
How much extra flooring should I buy?
10% for straight layouts, 15% for diagonal or offset, about 20% for herringbone. Keep a spare box for repairs.
How many boxes of flooring do I need for 200 square feet?
200 sq ft + 10% = 220 sq ft. That is 10 boxes of 22 sq ft or 11 boxes of 20 sq ft.
How do I convert square feet to square yards for carpet?
Divide by 9. Because carpet comes off 12 ft rolls, room width and seams decide how much you actually buy.
How many tiles do I need?
Area plus waste ÷ area of one tile. 180 sq ft + 10% with 12 × 24 in tiles (2 sq ft each) is 99 tiles.
Do I need underlayment for laminate or vinyl plank?
Laminate does, unless one is attached. Many vinyl planks have an attached pad. Check the manufacturer’s instructions, especially over concrete.
What this calculator assumes
- Waste is set by the layout you choose and applied to the total area including extra areas.
- Boxes are rounded up to whole boxes, so the cost is for the flooring you actually buy.
- Carpet adds 6 in of trim per strip and assumes strips run along the room length.
- Thinset, grout and underlayment are planning estimates. Follow the product labels.