Room and roll coverage
Room
Four walls: 2 × (length + width) × height. 12×10×8 → perimeter 44 ft × 8 ft = 352 sq ft.
Filled from the room, or type wall square feet if you already have it. Empty is not a roll count.
Simple square feet off the walls — not a hanging quote, not a catalog of openings.
A US single roll is often ~56 sq ft of paper. Prefill 56 is an example, not a spec. Type the number on the roll you are buying. Rolls, not gallons.
Pattern-repeat waste
0 in repeat ≈ 10%; 21 in repeat ≈ 15–20%. Default 15%. 352 sq ft at 56 sq ft/roll + 15% → 7.23 → 8 rolls.
Roll count
- Rolls ceil
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- Exact
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- Coverage
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- Waste
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Enter a room (12×10×8 → 352 sq ft) or wall square feet. Coverage comes from the roll. 352 sq ft at 56 sq ft/roll + 15% pattern-repeat waste → 8 rolls.
Coverage comes from the roll. The 56 sq ft/roll prefill is a typical US single-roll example, not a spec. Pattern repeat is why waste is 10–20% — not a painter’s gallon estimate. Not a hanging quote. Confirm the roll label. Nothing on this page leaves the browser.
How rolls are counted
Paint gallons come from the can. Wallpaper rolls come from the roll — a strip of paper, not a film of coating, and not flooring boxes.
walls = 2 × (length + width) × height net = walls − openings rolls = net / coverage_sq_ft_per_roll with_waste = rolls × (1 + waste/100) buy = ceil(with_waste) 12×10×8 room, four walls, no windows: perimeter 44 ft × 8 ft = 352 sq ft 56 sq ft/roll, 15% waste → 352×1.15/56 ≈ 7.23 → 8 rolls (ceil) 0% waste → ceil(352/56) = 7 rolls Pattern repeat adds waste. 0 in ≈ 10%; 21 in ≈ 15–20%. Not gallons. Not a hanging quote.
A 12×10×8 room at the example 56 sq ft/roll and 15% waste is 8 rolls, not a gallon of paint.
FAQ
Why rolls, not gallons?
Rolls cover a strip of wall, not a can of film. Paint is gallons of coating. Wallpaper is paper you hang in drops. A US single roll is often ~56 sq ft of paper, but you lose some to pattern repeat and waste. Coverage comes FROM THE ROLL (you can edit it, default 56), like paint-from-the-can — except the unit is a roll, not a gallon.
What does 56 sq ft per roll mean?
Coverage FROM THE ROLL: a typical US single roll is often about 56 square feet of paper. Type the number printed on the roll you are buying. This is not a brand table and not paint coverage from the can. Double rolls are often ~112 sq ft — type that if that is what you buy.
How does pattern repeat add waste?
Pattern repeat is extra paper so the motif lines up from drop to drop. 0 in repeat ≈ 10% waste; a 21 in repeat is more like 15–20%. Default here is 15% with chips at 10 / 15 / 20. That is not a painter’s gallon estimate. Bigger repeat, more waste.
How many rolls for a 12×10×8 room?
Four walls, no windows: perimeter 44 ft × 8 ft = 352 sq ft. At 56 sq ft/roll and 15% pattern-repeat waste, 352×1.15/56 ≈ 7.23 → 8 rolls (ceil). Same room at 0% waste is ceil(352/56) = 7 rolls. Empty wall or coverage is invalid, not a roll count.
Can I subtract doors and windows?
Yes, optionally, as simple square feet — not a door/window catalog. Type the opening area and it comes off the wall before the roll math. Openings cannot take the walls below a roll count of zero. Skip them and you buy paper for holes.
Is this a hanging quote?
No. Not a hanging quote, not a labor line, not a brand match. Roll-count math only: wall square feet (or a room), coverage from the roll, pattern-repeat waste, optional openings, round up. Related tools: paint (gallons), drywall, and the Acorn hub.