Square Footage Calculator - Area & Material Estimator

Whether you are redoing a bathroom floor, painting a bedroom, or pricing a commercial build-out, you need the same thing: accurate square footage plus a material estimate that accounts for waste. This calculator does both.

What This Calculator Does

Enter room dimensions (length, width, plus any cutouts or alcoves). The calculator returns:

• Net square footage (the actual floor area)
• Gross square footage (including walls under a 9-foot ceiling)
• Material needed for flooring, paint, tile, or wallpaper
• Waste factor added to the material order (10-20% by default)
• Total cost if you enter price-per-unit

Quick Example: 12 ft x 14 ft Bedroom

• Net area: 168 sq ft
• Walls: 2 x (12 + 14) x 8 = 416 sq ft of wall surface
• Ceiling: 168 sq ft
• Paint (one coat, walls only): 416 sq ft / 350 = 1.2 gallons (round up to 2)
• Flooring (with 10% waste): 168 x 1.10 = 185 sq ft to order
• Wallpaper (single roll covers ~57 sq ft, with 15% waste): 416 x 1.15 / 57 = 9 rolls

The calculator shows each of these in a single summary card.

Irregular Rooms

For L-shaped or T-shaped rooms:

1. Split into rectangles — measure each rectangle’s length and width
2. Add an entry per rectangle in the calculator
3. The total combines automatically

The calculator stores up to 8 rectangles. If you have more, calculate in batches and sum the totals.

Wall Paint Coverage

Standard paint coverage:

• One coat: ~350 sq ft per gallon (smooth drywall)
• Two coats: ~175 sq ft per gallon (most walls need 2)
• Texture / popcorn ceiling: ~250 sq ft per gallon
• Exterior stucco: ~200 sq ft per gallon

The calculator applies the appropriate divisor based on the surface type you select. For two coats, double the gallons shown.

Tile and Flooring

Tile and flooring materials are sold by the square foot in the U.S. and square meter in most of Europe. The calculator outputs both. For projects requiring cuts at walls and corners, the waste factor ensures you order enough:

The calculator defaults to 10% (straight lay). Pick the pattern you are using to get a realistic material order.

Cost Estimation

Enter price per square foot for the material (e.g. $4.50 for laminate flooring). The calculator multiplies by the gross material order (with waste) to give a single-line cost. Add a labor cost field for professional installation estimates (most flooring installers charge $2-5/sq ft for labor).

Limitations

• The calculator does not account for angled walls (vaulted ceilings, sloped attic walls). For those, split each wall into a rectangle and a triangle.
• It does not model room openings (doors, large windows) automatically — subtract them manually using the cutout field.
• For multi-story buildings, run each floor as a separate calculation.

Related Tools

• Unit Calculator — convert sq ft to sq m
• Tip Calculator — not related, but useful elsewhere
• Percentage Calculator — for waste factor adjustments