Interior calculators
Tile, flooring, drywall, paint and insulation.
- Tile CalculatorWork out how many tiles and boxes you need for a floor, wall or shower - with grout joints, layout waste, thinset bags, grout and cost.12 × 10 ft room, 12×12 tile → 130 tiles
- Paint CalculatorWork out how many gallons of paint you need for a room or a house exterior, minus doors and windows, with coats, primer, quarts or 5-gallon pails and cost.14 × 12 ft room, 2 coats → 2 gallons + 1 quart
- Drywall CalculatorWork out how many 4×8, 4×10 or 4×12 drywall sheets you need for walls and ceilings, plus screws, joint compound, tape and cost, with IRC code checks.14 × 12 ft room, 8 ft walls + ceiling → 19 sheets
About these calculators
The tile, drywall and paint calculators cover floors, walls, ceilings and showers. They tell you how many tiles and boxes, drywall sheets or gallons of paint to buy, plus the extras that are easy to forget: thinset and grout, screws, joint compound and tape, primer, and the cost of it all.
How to measure
Measure rooms wall to wall and walls from floor to where the material stops, in feet. Split L-shaped rooms into rectangles and add them up. For drywall and paint, doors and windows are subtracted at default sizes you can replace with your own; trim, doors and cabinets are measured separately for paint.
Before you start
- Read the label. Replace the starting values with the coverage printed on your paint can and the square feet per box on your tile.
- Use the actual tile size from the box or spec sheet, not the rounded nominal size.
- The waste allowance for tile and drywall is a rule of thumb: raise it for many corners, short walls, openings or cut-heavy layouts.
- If your home was built before 1978, or you don't know when, EPA says to assume old paint contains lead. Read the lead-safety advice on the paint calculator before you sand or scrape.