How to Measure a Room for Flooring
Updated
To measure a room for flooring, multiply its length by its width to get the square footage. For L-shaped or irregular rooms, split them into rectangles, measure each, and add the areas together. Then add 10% for waste (15% for diagonal layouts) before buying.
Measuring for flooring is simple in a square room and trips people up in everything else. Get it right and you buy the perfect amount; get it wrong and you either run short mid-install or overpay for boxes you'll never open.
This guide walks through measuring any room — including L-shapes, closets, and doorways — and how much extra to add so you're never caught short.
Key takeaways
- Square footage = length × width (in feet).
- Split L-shaped rooms into rectangles and add the areas.
- Add 10% waste for straight layouts, 15% for diagonal/herringbone.
- Include closets and doorways the flooring runs into.
- Always round up to full boxes and keep a spare.
Skip the math
Get instant numbers with the Flooring Calculator.
Step 1: Measure simple rectangular rooms
Measure the length and width of the room in feet and multiply them. A 12 ft × 15 ft room is 180 square feet. Measure at the widest points and round up to the nearest inch.
Step 2: Handle L-shaped and irregular rooms
Divide the room into rectangles, measure each one separately, then add the areas. An L-shaped room split into a 12×10 section and an 8×6 section is 120 + 48 = 168 square feet.
Step 3: Include closets and transitions
- Add the area of any closets the flooring continues into.
- Include doorways and thresholds where planks run through.
- Subtract large permanent fixtures only if they're truly excluded.
Step 4: Add a waste allowance
| Layout | Waste to add |
|---|---|
| Straight / standard | 10% |
| Diagonal | 15% |
| Herringbone / pattern | 15–20% |
Step 5: Convert to boxes
Divide your total square footage (with waste) by the coverage printed on each flooring box, then round up. Our flooring calculator does all of this — area, waste, and box count — from your room dimensions.