Flooring Calculator

The formula

Coverage and yield assumptions

Box coverage varies widely: laminate cartons often hold 18–25 sq ft, solid hardwood 18–24 sq ft, engineered wood 20–32 sq ft. Use the exact number on the label or spec sheet; it already accounts for the actual board dimensions, not the nominal ones.

Measuring rooms and closets

Measure wall to wall at the widest points, ignoring baseboards. Include closets, pantry floors and the space under appliances you will slide back in, such as the refrigerator alcove. For L-shaped or irregular plans, break the floor into rectangles, find each area and add them. Bay windows and angled walls can be squared off: the extra counts as waste you would have spent anyway.

Doorways need a transition strip or a continuous run into the next room. If floors flow from room to room without thresholds, treat the whole connected space as one area so you can plan board direction and expansion gaps together.

Board direction and layout

Run planks parallel to the longest wall or toward the main light source so seams are less visible. In narrow hallways, run boards lengthwise. Stagger end joints by at least 6 in (follow the manufacturer's minimum) and avoid H-patterns where joints line up every other row. Plan the last row so it is not narrower than about 2 in; rip the first row if needed.

Subfloor, underlayment and acclimation

The subfloor must be flat, dry and sound. Most floating floors call for flatness within 3/16 in over 10 ft. Over concrete, use a vapor retarder; many laminate and engineered products require a foam or felt underlayment unless one is pre-attached. Solid hardwood is nailed to a wood subfloor and should acclimate to the home's normal temperature and humidity; the National Wood Flooring Association recommends checking moisture content of both subfloor and flooring before installing.

Expansion gaps and trim

Wood and laminate move with humidity, so leave the expansion gap the maker specifies, typically 1/4 to 1/2 in, at every wall and fixed object. Baseboard or quarter-round covers the gap. Undercut door casings with a jamb saw so planks slide underneath instead of scribing around them.

Ways to save

• Compare price per square foot, not per box, since cartons differ.
• Keep unopened boxes and receipts; most stores accept returns.
• Save one box after the job for future repairs.

Common mistakes to avoid

• Using nominal plank sizes instead of the coverage printed on the box.
• Forgetting closets and the space under appliances.
• Skipping acclimation for solid wood, leading to gaps or cupping.
• Leaving no expansion gap at walls for floating floors.
• Buying exactly the area with no waste, then running short on the last row.

Waste factor

Use 5–7% for a simple rectangle with straight-lay planks, 10% for typical rooms with closets and doorways, and 15–20% for diagonal or herringbone patterns, many angled walls, or boards with lots of natural defects you want to cull.

Imperial and metric

Switch the toggle above the inputs to enter ft ↔ m, sq ft ↔ m². The page converts metric entries to imperial before calculating, using NIST factors (1 ft = 0.3048 m, 1 in = 2.54 cm), and shows key results in both systems.

Worked examples

Living room, 15 × 12 ft

Inputs: room length 15 ft; room width 12 ft; coverage per box 20 sq ft; waste factor 10%.

Result: You need 198 sq ft of flooring.

• Units to buy (rounded up): 10 boxes
• Room area: 180 sq ft (16.7 m²)
• Area with waste: 198 sq ft (18.4 m²)
• Boxes to buy: 10

Open-plan area with herringbone

Inputs: room length 24 ft; room width 18 ft; coverage per box 22.5 sq ft; waste factor 20%; cost per unit $89.

Result: You need 518 sq ft of flooring.

• Units to buy (rounded up): 24 boxes
• Room area: 432 sq ft (40.1 m²)
• Area with waste: 518 sq ft (48.2 m²)
• Boxes to buy: 24
• Estimated material cost: $2,136.00

Small office, straight lay

Inputs: room length 11 ft; room width 10 ft; coverage per box 24 sq ft; waste factor 5%.

Result: You need 116 sq ft of flooring.

• Units to buy (rounded up): 5 boxes
• Room area: 110 sq ft (10.2 m²)
• Area with waste: 116 sq ft (10.7 m²)
• Boxes to buy: 5

Quick reference for common sizes

The table repeats the first worked example at smaller and larger sizes, keeping every other setting the same, so you can see how the flooring calculator result scales.

Limitations

This is a material estimate. It does not size underlayment rolls, transitions or stair treads, and it assumes the box coverage you enter is accurate. Stairs are counted by tread and riser, not floor area.