7 calculators
Paint, Flooring & Wall Calculators
Calculate paint gallons, flooring boxes, tile, carpet, drywall sheets, wallpaper rolls and grout for any room, with openings, waste allowance and cost.
Which calculator do you need?
- Painting walls and ceilings: the paint calculator gives gallons per coat, primer and the cans to buy.
- New walls or a basement: the drywall calculator counts sheets, screws, tape and compound.
- Laminate, vinyl plank or hardwood: the flooring calculator turns room sizes into boxes.
- Floor and wall tile: the tile calculator counts tiles and boxes with joints and layout waste, and the grout calculator adds the grout.
- Carpet: the carpet calculator plans strips from the roll width, which is what you actually pay for.
- Wallpaper: the wallpaper calculator counts full-height strips and pattern repeat.
Floor area or wall area?
Flooring, tile and carpet start from floor area: length × width for each room. Paint, drywall and wallpaper start from wall area: the room’s perimeter (2 × length + 2 × width) times the wall height, less doors and windows. A 12 × 12 ft room has a 144 ft² floor but 384 ft² of walls at 8 ft high, which is why a room’s paint is never estimated from its floor size.
Why you buy more than you measure
Interior finishes are sold in fixed packages, and every one rounds differently. Flooring and tile come in boxes; paint in quarts, gallons and 5-gallon buckets; carpet off rolls 12 ft wide; wallpaper in rolls that only give a whole number of strips; drywall in 4 ft wide sheets. On top of that, cuts at walls, corners and doorways create waste: about 10% for straight-laid floors, 15% for diagonal or herringbone layouts, and more for small rooms. Each calculator shows the exact area, the allowance and the rounded purchase separately, so you can see what you are paying for.
A sensible order of work
- Hang and finish drywall, then prime new drywall.
- Paint ceilings, then walls, before new flooring goes down.
- Install tile and hard flooring; carpet goes in last, after painting is finished.
- Fit baseboard and do final touch-ups, using the spare paint and flooring you kept.
Buying tips
- Buy one lot. Paint, tile, flooring and wallpaper vary slightly from batch to batch; buy the whole job at once and check lot numbers.
- Keep spares. A box of flooring, a few tiles, a roll of wallpaper and a quart of paint make future repairs invisible.
- Read the label. Coverage per gallon, box coverage and roll sizes vary by product, and every calculator lets you enter the real figure.