Flooring Guide: Everything You Need to Estimate
To find how much flooring you need, multiply the room length by width for the area, then add 5–15% for waste and cuts. Divide by the coverage per box to get the number of boxes. A 15×12 ft room needs about 198 sq ft with 10% waste, costing roughly $600–$2,000 installed depending on material.
Get exact numbers
Use the free Flooring Calculator to estimate your project.
How to estimate flooring
Formula: Flooring (ft²) = Length × Width × (1 + waste %); Boxes = area ÷ coverage per box
- Measure the room. Multiply length × width. Split L-shaped rooms into rectangles and add them.
- Add a waste factor. 5% for straight lay, 10% standard, 15% for diagonal or patterned layouts.
- Divide by box coverage. Check the carton — most boxes cover 18–24 sq ft.
- Round up. Always round boxes up and keep a spare for future repairs.
Example: A 15 ft × 12 ft room: 180 ft² × 1.10 = 198 ft². At 20 ft² per box that's 10 boxes.
Common mistakes to avoid
Forgetting the waste factor
Cuts at walls and around obstacles waste material. Add 10% for straight lay and 15% for diagonal or herringbone.
Measuring an L-shaped room as one rectangle
Split irregular rooms into rectangles, calculate each, and add them before applying waste.
Not buying a spare box
Dye lots change between runs. Keep an extra box sealed for future repairs so it matches.
Ignoring underlayment and transitions
Underlayment, trim, and transition strips add to the budget and aren't in the flooring square footage.