How to calculate flooring
Flooring is sold by the square foot but packed in boxes, so start with the floor area, add waste for cuts, and divide by the coverage printed on the box. Always round up to whole boxes.
Flooring to buy = floor area × (1 + waste %)
Boxes = flooring to buy ÷ square feet per box, rounded up
Example: a 16 × 14 ft living room is 224 sq ft. With 10% waste for a straight layout you need 246.4 sq ft. At 20 sq ft per box, that's 12.3 boxes, so buy 13. For underlayment, 224 sq ft takes 3 rolls of 100 sq ft.
Waste allowance by layout
| Situation | Add |
|---|---|
| Large, open, rectangular room | 5–8% |
| Typical room, straight layout | 10% |
| Small rooms, halls, many doorways | 12–15% |
| Diagonal layout | 15% |
| Herringbone or chevron | 20% or more |
What else to buy
- Transitions: T-molding, reducers or thresholds wherever the new floor meets another floor type or crosses a doorway.
- Baseboard or quarter round: floating floors need an expansion gap at the walls, covered by trim. Use the baseboard calculator to size it.
- Vapor barrier: usually required over concrete slabs and basements.
Let laminate and hardwood acclimate in the room for the time the manufacturer recommends before installing, usually 48 hours or more.
Frequently asked questions
How much extra flooring should I buy?
Buy about 10 percent extra for a straight installation in a typical room, and 15 percent or more for diagonal or herringbone layouts, small rooms with many cuts, or hallways with lots of doorways.
How many boxes of flooring do I need?
Divide the square footage you need (including waste) by the square feet per box printed on the carton, then round up. Laminate and vinyl plank boxes commonly hold around 15 to 25 square feet, but check your product.
Do I need underlayment?
Most floating laminate floors need a foam underlayment unless the planks have one attached. Many vinyl plank products include an attached pad. Over concrete, a vapor barrier is usually required. Follow the flooring maker's instructions so you don't void the warranty.
How do I measure multiple rooms?
Measure each room's length and width, multiply, and add the results together. Include closets and the space under appliances you plan to floor under. Enter the total using the "I know the area" option.
Should I keep leftover flooring?
Yes. Keep at least one full box for repairs. Colors and finishes change between production runs, and discontinued styles can be impossible to match later.