Flooring is sold by the box, but priced and planned by the square foot. This calculator bridges the two: it finds the floor area, adds an allowance for cuts and mistakes, and tells you how many full boxes to order and what they will cost. It works for laminate, luxury vinyl plank (LVP), engineered wood, solid hardwood and any product sold in boxes.
How to use the flooring calculator
- Measure the room wall to wall at floor level. Use the larger number if the walls aren't parallel.
- Enter the number of identical rooms, such as two bedrooms of the same size.
- Choose a waste allowance. 10% suits most straight installs.
- Enter the coverage per box from the product label — it varies from about 15 to 30 sq ft depending on plank size.
- Add the price per square foot to see the material cost for the whole boxes you will buy.
Flooring formula
Order area = Area × (1 + waste% ÷ 100)
Boxes = ⌈ order area ÷ coverage per box ⌉
Cost = boxes × coverage per box × price per sq ft
The cost is based on whole boxes because that is what you pay for — even if the last box is only partly used.
Worked example
A living room measures 15 ft × 12 ft. The vinyl plank comes in boxes of 20 sq ft at $2.50 per sq ft.
- Floor area: 15 × 12 = 180 sq ft
- Add 10% waste: 180 × 1.10 = 198 sq ft
- Boxes: 198 ÷ 20 = 9.9 → 10 boxes
- Cost: 10 × 20 × $2.50 = $500
Waste allowance by layout
| Layout | Typical allowance | Why |
|---|---|---|
| Straight lay, simple rectangle | 5–10% | Offcuts at each row end can often start the next row |
| Straight lay, many corners or doorways | 10–12% | More short, unusable pieces |
| Diagonal | 15% | Every edge piece is cut at an angle |
| Herringbone or chevron | 15–20% | Pattern matching and angled ends |
Boxes needed per room size
With 10% waste and 20 sq ft per box.
| Room | Floor area | With 10% | Boxes |
|---|---|---|---|
| 10 × 10 ft | 100 sq ft | 110 sq ft | 6 |
| 10 × 12 ft | 120 sq ft | 132 sq ft | 7 |
| 12 × 12 ft | 144 sq ft | 158.4 sq ft | 8 |
| 12 × 15 ft | 180 sq ft | 198 sq ft | 10 |
| 14 × 16 ft | 224 sq ft | 246.4 sq ft | 13 |
| 15 × 20 ft | 300 sq ft | 330 sq ft | 17 |
| 20 × 20 ft | 400 sq ft | 440 sq ft | 22 |
Before you order
- Buy all boxes at once so they come from the same production run — color can vary slightly between batches.
- Let the flooring acclimate in the room if the manufacturer asks for it.
- Remember underlayment and transitions. Underlayment is usually sold by the roll in square feet; thresholds and reducers are bought per doorway.
- Keep a spare box for future repairs.
For tile floors use the Tile Calculator, which accounts for grout lines. Need just the area? The Square Footage Calculator handles circles and triangles too.
Frequently asked questions
How do I calculate how much flooring I need?
Multiply the room's length by its width to get square feet, add 10% for waste, then divide by the square feet in one box and round up. A 15 × 12 ft room is 180 sq ft; with 10% waste that is 198 sq ft, or 10 boxes of 20 sq ft.
How much extra flooring should I buy?
About 10% for a straight layout and 15% for diagonal or herringbone patterns. Rooms with lots of corners, closets or doorways waste more. A spare box is also handy for future repairs, since dye lots and styles get discontinued.
Do I include closets in the flooring measurement?
Yes, if the closet gets the same floor. Measure it as its own rectangle and add it, or enter it as a second room. Leave out areas under permanent cabinets or kitchen islands.
Can I return extra boxes of flooring?
Many stores accept unopened boxes, but policies vary — check before you buy. Ordering everything at once also helps make sure all boxes come from the same production batch.
How do I measure an L-shaped room for flooring?
Split it into two rectangles, measure each, and add the areas. Use the rooms field for identical areas, or run the calculator twice and add the boxes.