Flooring Calculator
- Updated
- Imperial and metric
- Free, no sign-up
Results
184.8 ft² of flooring including waste, 10 boxes
Pieces are total length ÷ piece length, rounded up. Buy a spare piece or two for corner cuts and short walls.
How to use the flooring calculator
- Measure each room's length and width at the widest points. Include closets and alcoves that get the same floor. Split an L-shaped room into two rectangles and add each one with + Add area.
- Choose the layout. It sets a typical waste allowance, which you can change if the manufacturer or your installer recommends a different figure.
- Enter the coverage per box. It is printed on the box or the product page, in square feet or square meters.
- Optionally enter the underlayment roll coverage, the number of doorways and the baseboard length you will buy.
- Add the price per square foot or per box to estimate the cost.
Flooring formula
Area to buy = Floor area × (1 + Waste %)
Boxes = Area to buy ÷ Coverage per box, rounded up
Baseboard = Sum of room perimeters − Doorways × Doorway width
In metric, measure in meters and the area comes out in square meters. Because flooring is sold in whole boxes, the cost is based on the area in the boxes you buy, not the exact area of the room.
Worked example: a living room and a bedroom
A 14 × 12 ft living room (168 ft²) and an 11 × 10 ft bedroom (110 ft²) add up to 278 ft². With a straight layout and 10% waste you need 305.8 ft². At 20 ft² per box that is 15.29 boxes, so you buy 16 boxes, which hold 320 ft². Underlayment in 100 ft² rolls takes 3 rolls.
For baseboard, the two perimeters are 52 ft and 42 ft. Leaving out two 3 ft doorways gives 88 ft, or 11 pieces of 8 ft baseboard. Buy a spare piece or two for corner cuts.
Boxes for common room sizes
Boxes of 20 ft² each, one 3 ft doorway and 8 ft baseboard pieces. Check your product's coverage per box, since it varies with the plank size and the brand.
| Room | Floor area | Boxes, straight (10%) | Boxes, diagonal or herringbone (15%) | Baseboard |
|---|---|---|---|---|
| 10 × 10 ft | 100 ft² | 6 | 6 | 37 ft (5 pieces) |
| 10 × 12 ft | 120 ft² | 7 | 7 | 41 ft (6 pieces) |
| 12 × 12 ft | 144 ft² | 8 | 9 | 45 ft (6 pieces) |
| 12 × 15 ft | 180 ft² | 10 | 11 | 51 ft (7 pieces) |
| 14 × 16 ft | 224 ft² | 13 | 13 | 57 ft (8 pieces) |
| 15 × 20 ft | 300 ft² | 17 | 18 | 67 ft (9 pieces) |
| 20 × 20 ft | 400 ft² | 22 | 23 | 77 ft (10 pieces) |
How much waste to allow
These are typical allowances, and the calculator uses them as defaults. Rooms with many corners, closets or doorways need more. Some manufacturers give their own figure in the installation instructions; use it if they do.
| Layout | Default waste | Why |
|---|---|---|
| Straight (standard) | 10% | Cuts at the ends of rows and along the last row. End offcuts can often start the next row. |
| Diagonal | 15% | Every piece along the walls is cut at an angle, and those offcuts are harder to reuse. |
| Herringbone or chevron | 15% | Short pieces and angled cuts at every edge of the room. |
Tips for buying flooring
- Buy it all at once. Color and texture can vary between production lots, so buy every box together and check that the lot numbers match.
- Keep a spare box. A few leftover planks make it much easier to repair a damaged board later.
- Follow the installation instructions. Many products need time to acclimate in the room, and floating floors need an expansion gap at the walls, which the baseboard or quarter-round covers. The instructions give the time and the gap size.
- Check the underlayment rules. Some vinyl plank and laminate comes with a pad attached, and over concrete a moisture barrier is often required. Use what the manufacturer specifies, because the wrong underlayment can affect the warranty.
- Doing a tiled room too? Use the tile calculator and the grout calculator. If the walls are being redone first, the drywall calculator covers sheets, mud and tape.
Frequently asked questions
How much extra flooring should I buy?
A common allowance is 10% for a straight layout and about 15% for diagonal, herringbone or chevron layouts, which need more angled cuts. Rooms with many corners, closets or doorways may need more, and some manufacturers state their own figure. The calculator sets the waste from the layout you choose, and you can change it.
How many boxes of flooring do I need for a 12×12 room?
A 12 × 12 ft room is 144 sq ft. With 10% waste you need 158.4 sq ft, which is 8 boxes if each box covers 20 sq ft. A diagonal layout with 15% waste needs 165.6 sq ft, or 9 boxes. Coverage per box varies between products, so use the figure printed on the box.
How do I measure a room for flooring?
Measure the length and width at the widest points and multiply them. Include closets and alcoves that get the same floor. For an L-shaped room, split it into two rectangles, measure each one and add them together; the calculator lets you add as many areas as you need.
How much baseboard do I need?
Add up the perimeter of each room and subtract the width of each doorway. A 12 × 12 ft room has a 48 ft perimeter; with one 3 ft doorway that is 45 ft, or 6 pieces of 8 ft baseboard. Buy a spare piece for corner cuts and short walls.
Do I need underlayment under my flooring?
It depends on the product. Laminate without an attached pad usually needs one, while some vinyl plank and laminate comes with the pad built in. Over a concrete slab, a moisture barrier is often required. Follow the manufacturer's installation instructions, because the wrong underlayment can affect the warranty.