Flooring Square Footage with Waste
Measure the room, add a waste allowance (commonly about 10% for straight lay, 15% for diagonal or herringbone), then divide by the square feet per box and round up.
Why you need extra
Every row ends at a wall, so boards and tiles get cut, and the offcut is often too short to start the next row. Some pieces have defects you'll want to skip, and you'll want a few spares for future repairs. The waste allowance covers all of that.
How much waste to add
| Situation | Common allowance |
|---|---|
| Simple rectangular room, straight lay | about 5–10% |
| Rooms with closets, angles or many doorways | about 10–15% |
| Diagonal layout | about 15% |
| Herringbone / chevron | 15–20% or more |
These are general rules of thumb. Manufacturers and installers sometimes specify their own figure, so follow it when they do.
Worked example
A 15' 4" × 12' room: 15.333 × 12 = 184 sq ft. Add 10% waste: 184 × 1.10 = 202.4 sq ft. The flooring comes in boxes of 20 sq ft: 202.4 ÷ 20 = 10.12, so buy 11 boxes (220 sq ft). Always round boxes up. If you can return unopened boxes, check the store's return policy before you buy.
Measuring tips
- Measure into door jambs and under where baseboards will sit. The flooring runs to the wall, under the trim.
- Add closets and hallways as separate areas, using the optional extra area above.
- Don't subtract small fixed items like kitchen islands unless you are certain. Cutting around them creates waste anyway.
- Buy all boxes from the same production lot so colour matches.
Square feet vs square yards
Hard flooring is usually sold per square foot, while carpet is often quoted per square yard. Divide square feet by 9 to compare: 184 sq ft = 20.4 sq yd. More in sq ft to sq yd for carpet.
Related
FAQ
How much extra flooring should I buy?
A common allowance is about 10% for straight lay in a simple room and about 15% for diagonal layouts, with more for herringbone or complex rooms.
How many boxes of flooring do I need?
Multiply the room's square footage by 1 + waste %, divide by the square feet per box and round up. 184 sq ft + 10% = 202.4 sq ft ÷ 20 = 11 boxes.
Do I include closets?
Yes, if they get the same flooring. Add them as separate areas.