Flooring Calculator
Find how many boxes of flooring to buy, with the right waste for your layout.
Waste factor
How much extra flooring to buy
Extra covers cuts at walls, damaged pieces and pattern matching. The more corners and angles, the more you need.
Simple room
A plain rectangle with a straight lay.
Most rooms
Straight lay with a few corners or doorways.
Diagonal or tile
Angled cuts at every wall.
Herringbone
Chevron and herringbone patterns.
Worked example
How to calculate flooring
A 344 sq ft floor, straight lay, with boxes that cover 20 sq ft each.
- 1 · Floor area344 sq ftLength × width, room by room
- 2 · Add 10% waste378.4 sq ft344 × 1.10
- 3 · Divide by box18.92378.4 ÷ 20 sq ft per box
- 4 · Round up19 boxesCovers 380 sq ft
Before you buy
Flooring tips that save a second trip
- Buy from one batchColor and finish can differ between production runs.
- Keep a spare boxIt makes future repairs match.
- Include closetsIf the flooring runs into them, add their area.
- Skip fixed cabinetsLeave out islands and cabinets the floor won’t go under.
By material
Waste factor and box size by flooring type
Typical starting points. Check the coverage printed on your box and the installation guide for your product.
| Flooring | Typical box coverage | Straight lay waste | Diagonal or pattern |
|---|---|---|---|
| Laminate | 18–24 sq ft | 8–10% | 15% |
| Luxury vinyl plank (LVP) | 20–30 sq ft | 5–10% | 15% |
| Engineered or solid hardwood | 18–32 sq ft | 10% | 15–20% |
| Porcelain or ceramic tile | 8–16 sq ft | 10% | 15–20% |
| Carpet | Sold by sq ft or sq yd (12 ft rolls) | 10% | 15% with seams |
Tricky areas
Closets, doorways, hallways and stairs
Closets and doorways
Add each closet as its own room. Add the strip under each door (usually 3 × 0.5 ft) if the floor runs through it.
Hallways
Measure them as long rectangles. Narrow halls create more short offcuts, so use at least 10% waste.
Stairs
Measure one tread plus one riser, multiply by the stair width, then by the number of steps. Order stair nosing separately.
How do I calculate how much flooring I need?
Multiply the room's length by its width to get square feet, add 10% for waste, then divide by the square feet in one box and round up to a whole box.
How much extra flooring should I buy?
Add 10% for most rooms with a straight layout, 15% for diagonal layouts and tile, and 20% for herringbone or chevron patterns. Simple rectangular rooms may only need 5%.
How many boxes of flooring do I need for 500 sq ft?
With 10% waste you need 550 sq ft. If each box covers 20 sq ft, that is 27.5 boxes, so buy 28. Check the coverage printed on your box, as it varies by product.
Should I include closets and subtract cabinets?
Include closets if the flooring will run into them. Leave out fixed cabinets and kitchen islands if the floor will not go underneath them.
How many square feet are in a box of flooring?
It depends on the product. Laminate and vinyl plank boxes often cover around 15 to 25 sq ft. The exact coverage is printed on the box.
How much waste should I add for tile?
Use about 10% for a straight tile lay and 15–20% for diagonal or patterned tile, plus a few spare tiles for future repairs.
How do I calculate flooring for stairs?
Measure one tread plus one riser, multiply by the stair width, then by the number of steps. Stair nosing is usually sold by the piece.
Do I need underlayment for the same area?
Yes. Underlayment covers the same floor area, usually with about 5% extra. Check whether your flooring already has a pad attached.