How to Calculate How Much Flooring You Need
Step-by-step instructions for measuring your rooms and calculating exactly how much flooring to buy, including waste factors for different installation patterns.
How to Calculate How Much Flooring You Need
One of the most common and costly mistakes homeowners make when buying flooring is getting the quantity wrong. Buy too little, and you can't match the same product later. Buy too much, and you've wasted money. Getting this calculation right before you walk into a flooring store — especially a liquidator where inventory is limited — is essential. Here's exactly how to do it.
What You'll Need
- A tape measure (25-foot minimum)
- A notepad or phone to record measurements
- A basic calculator
Step 1: Measure Each Room
Measure every room that will receive new flooring. For each room, you need two numbers: the longest length and the widest width.
For a simple rectangular room, the calculation is straightforward:
Square footage = Length (ft) x Width (ft)
Example: A bedroom that is 12 feet by 14 feet = 168 square feet.
Dealing With Irregular Room Shapes
Most rooms aren't perfect rectangles. For L-shaped rooms or rooms with alcoves, break the space into rectangular sections and add them together.
Example: An L-shaped living room can be measured as two rectangles. If one section is 14' x 20' (280 sq ft) and the connecting section is 8' x 10' (80 sq ft), the total is 360 square feet.
Measuring Around Fixed Objects
Measure the full room dimensions, not around furniture or islands. Flooring goes under furniture in most cases, and cabinets and islands sit on top of the subfloor, not the flooring.
For kitchen islands that are built in and won't be floored under, measure the island footprint and subtract it — though in most cases the additional material isn't worth worrying about unless it's a large island.
Step 2: Add All Rooms Together
Once you have square footage for each room, add them together.
Example:
- Living room: 360 sq ft
- Kitchen: 180 sq ft
- Hallway: 45 sq ft
- Bedroom 1: 168 sq ft
- Bedroom 2: 144 sq ft
- Total: 897 square feet
Step 3: Apply the Waste Factor
This is the step many buyers skip — and it causes problems. Waste factor accounts for cuts at walls, pattern matching, and any installation mistakes. The right waste factor depends on your installation pattern:
Standard Straight Lay
Add 10% to your total square footage.
897 sq ft x 1.10 = 987 square feet to purchase
Diagonal Installation
Add 15% because diagonal cuts produce more waste at walls.
897 sq ft x 1.15 = 1,031 square feet to purchase
Herringbone or Chevron Pattern
Add 15–20%. These patterns are cut-intensive and waste is higher.
897 sq ft x 1.18 = 1,058 square feet to purchase
Plank Tile (Large Format)
Add 10% for straight lay, 15% for diagonal or offset patterns.
Step 4: Convert to Boxes or Cartons
Flooring is sold by the box or carton, each covering a fixed number of square feet. The coverage per box is printed on the packaging. To find how many boxes you need:
Number of boxes = Total square footage needed ÷ Coverage per box (rounded up)
Example: You need 987 square feet. Each box covers 22 square feet. 987 ÷ 22 = 44.86, so you need 45 boxes.
Always round up, never down.
Step 5: Note the Dye Lot or Shade Lot Number
This matters more than most people realize. Even within the same product SKU, flooring is produced in batches called dye lots or shade lots. Products from different lots can have subtle color variations that are invisible looking at individual planks but become obvious when installed side by side.
When buying at a liquidator, make sure all the boxes you're purchasing are from the same lot number. Lot numbers are printed on the side of the box — look for it before paying.
Staircase Calculation
Stairs require separate measurement. For each step, measure:
- Tread depth (typically 10–11 inches)
- Tread width (typically 36–42 inches)
- Add tread and riser height if you're cladding the riser too
A typical staircase of 14 steps at 11" deep x 36" wide = about 38 square feet for treads alone. Add 15–20% waste for stair applications.
Closet Calculation
Include closets if you're running the same flooring through. Measure each closet and add to your total before applying the waste factor.
Tips for Liquidator Shopping
When buying at a flooring liquidator specifically, a few extra tips apply:
Buy all the boxes you need in one trip. Liquidators sell out of specific products and don't reorder. You cannot come back for two more boxes next week.
Buy a few extra boxes beyond your waste calculation. Store them for future repairs. A matching plank years from now is worth more than what you paid for it.
Verify all boxes are from the same lot before purchasing. Ask staff to pull boxes from back stock if needed to complete your quantity from a single lot.
Confirm the coverage per box before calculating — it varies by product and even by box orientation.
Quick Reference Waste Factor Chart
| Installation Pattern | Waste Factor |
|---|---|
| Straight/parallel | 10% |
| Diagonal (45°) | 15% |
| Herringbone | 15–20% |
| Chevron | 15–20% |
| Stairs | 15–20% |
| Irregular or complex rooms | 15% |
The Bottom Line
Accurate measurement is the foundation of a successful flooring project. Take the time to measure correctly, apply the appropriate waste factor, and verify your dye lot numbers. Doing this before you shop — especially at a liquidator — ensures you get what you need without costly shortfalls.