How to measure a room for flooring
To measure a room for flooring, multiply its length by its width to get the square footage, then add about 10% for waste. A 12 × 15 ft room is 180 sq ft — roughly 198 sq ft once you include waste. Here's how to do it accurately, even in tricky rooms.
What you'll need
- A tape measure (a laser measure is faster for big rooms)
- Paper or your phone to jot down numbers
- A calculator — or ours, linked below
Step 1: Measure length and width
Measure the room at its longest and widest points, in feet. If the baseboards are off, measure wall to wall at floor level. Write down both numbers.
Step 2: Multiply for square footage
Length × width = area in square feet. A 12 × 15 ft room is 180 sq ft. This is the bare floor area before any waste.
Step 3: Handle odd-shaped rooms
For L-shaped rooms or spaces with alcoves, split the floor into rectangles, measure each one, and add the areas together. Include closets and doorways you'll be flooring. For a bay window or angled nook, measure the largest rectangle that contains it — the extra becomes part of your waste buffer.
Step 4: Add a waste allowance
Always buy more than the exact area to cover cuts, mistakes, and future repairs.
| Layout | Add for waste |
|---|---|
| Straight, simple room | 8–10% |
| Rooms with many cuts or angles | 10–15% |
| Diagonal layout | 15% |
| Herringbone or chevron | 15–20% |
Let the calculator do steps 2–5
Enter your measurements and box size into our flooring calculator to get the square footage, waste, number of boxes, and cost in one go.
Open the Flooring CalculatorStep 5: Convert to boxes
Flooring is sold by the box, and coverage per box varies by product. Divide your total square footage (including waste) by the coverage printed on the carton, then round up to the next whole box. Buy one extra box and keep it — if the line is discontinued later, you'll have a perfect-match repair on hand.
Common mistakes to avoid
- Forgetting waste. Ordering the exact area almost always leaves you short.
- Mixing dye lots. Buy it all at once so planks match.
- Ignoring transitions. Doorway trims and thresholds are usually sold separately.