Square Footage for Flooring, Tile and Carpet
Measuring the room is the easy part. The mistakes that cost money happen between the measurement and the order.
To calculate flooring square footage, measure the room area and add a waste allowance — 10% for a straight lay, 15% for diagonal patterns. A 300 sq ft room needs 300 × 1.10 = 330 square feet of flooring. Divide by the coverage per box and round up to get the number of boxes.
Start with an accurate room measurement
Everything downstream depends on this. Measure at floor level, wall to wall, at the widest points — the full method is in how to measure a room.
Include every area you will actually be flooring:
- Closets and pantries
- Alcoves and bay windows
- Under-stair spaces
- The area under radiators and freestanding furniture
Exclude built-in cabinetry that sits directly on the subfloor, and kitchen islands that are permanently fixed.
For multiple rooms, the room calculator totals them as you go.
Waste allowance
Waste is not padding — it is a structural part of the calculation. Every cut at a wall, doorway or corner leaves an offcut, and some boards arrive damaged.
| Layout | Waste | Why |
|---|---|---|
| Straight lay, rectangular room | 10% | Minimal cutting |
| Straight lay, many corners or alcoves | 12–15% | More cuts, more offcuts |
| Diagonal (45°) | 15% | Every perimeter piece is cut at an angle |
| Herringbone or chevron | 15–20% | Complex pattern, high offcut rate |
| Large-format tile (24 in+) | 20% | One bad cut wastes a lot of material |
| Patterned or directional material | 15–20% | Pattern matching drives waste up |
For a 300 sq ft room with a straight lay: 300 × 1.10 = 330 square feet to order.
Working out boxes
Flooring is sold by the box, with coverage printed on the packaging — commonly 18 to 24 sq ft for laminate and engineered wood.
Divide your total including waste by the coverage per box, then always round up. You cannot buy a partial box.
For 330 sq ft at 22.5 sq ft per box: 330 ÷ 22.5 = 14.67 → order 15 boxes.
The flooring calculator does the waste and box maths together, and adds a cost estimate.
Order it all at once
This is the single most expensive mistake in a flooring job, and it is entirely avoidable.
Flooring is manufactured in dye lots — production batches that vary slightly in colour and grain. Material from a different lot placed next to the original is often visibly different, particularly in natural light.
So:
- Order everything in one purchase
- Check that all boxes carry the same lot number when they arrive
- Keep one spare box after the job for future repairs
A single spare box is far cheaper than discovering, in three years, that your product has been discontinued.
Notes by material
Hardwood and engineered wood. Sold by the box; some suppliers also quote linear feet, in which case see square feet vs. linear feet. Acclimatise the boxes in the room for 48 to 72 hours before installation so the wood adjusts to the humidity.
Laminate and LVP. Sold by the box, typically 20 to 24 sq ft. More dimensionally stable than wood, so acclimatisation matters less, though most manufacturers still recommend it.
Tile. Check whether the price is per tile or per square foot — a 12 × 12 in tile is 1 sq ft, an 18 × 18 in tile is 2.25 sq ft, and a 24 × 24 in tile is 4 sq ft. See the inches conversion guide. Large-format tile needs the higher waste allowance because each cut wastes more.
Carpet. Comes on rolls, almost always 12 ft wide. This changes the maths entirely: a room 13 ft wide needs either a seam or a 26 ft width of roll, wasting a strip 11 ft wide down the length. Ask the supplier to work out the actual cut — you frequently pay for more than your bare square footage. Carpet is also often priced by the square yard, which is 9 square feet.
Vinyl sheet. Same roll-width logic as carpet, usually in 6 ft or 12 ft widths.
Quick reference
| Room area | +10% waste | +15% waste | Boxes at 20 ft²/box (10%) |
|---|---|---|---|
| 100 sq ft | 110 sq ft | 115 sq ft | 6 boxes |
| 200 sq ft | 220 sq ft | 230 sq ft | 11 boxes |
| 300 sq ft | 330 sq ft | 345 sq ft | 17 boxes |
| 500 sq ft | 550 sq ft | 575 sq ft | 28 boxes |
| 800 sq ft | 880 sq ft | 920 sq ft | 44 boxes |
| 1,200 sq ft | 1,320 sq ft | 1,380 sq ft | 66 boxes |
Do not forget the extras
Square footage covers the flooring itself. A complete order usually also needs:
- Underlayment — same square footage, unless the flooring has it pre-attached
- Transition strips — linear feet, at every doorway and material change
- Baseboard or quarter round — linear feet, equal to the room perimeter
- Adhesive, grout or spacers — per the manufacturer’s coverage rate
- Tack strip and padding for carpet — perimeter and area respectively
Costing it out: multiply your total by the price per square foot using the price per sqft calculator, then add the extras and labour.
Frequently asked questions
How much extra flooring should I buy?
Add 10% for a simple rectangular room with a straight lay, 15% for diagonal or herringbone patterns and rooms with many corners, and up to 20% for large-format tile.
How do I calculate how many boxes of flooring I need?
Divide the total square footage including waste by the coverage per box printed on the packaging, then round up. 330 sq ft at 22.5 sq ft per box means 15 boxes.
Why should I order all my flooring at once?
Flooring is manufactured in dye lots and colour varies slightly between production batches. A top-up order placed later can be a visibly different shade from the original.
Do I include closets in the flooring measurement?
Yes, if you are laying flooring inside them. Measure each closet as a small rectangle and add it to the room total.
How is carpet measured differently?
Carpet comes on rolls of a fixed width, usually 12 feet. The practical amount you buy depends on how the roll cuts into your room, so you often pay for more than your bare square footage.