How Much Paint Do I Need? Gallon and Quart Coverage, Room by Room
How much paint do I need? Measure wall area, subtract doors and windows, multiply by two coats and divide by 350–400 sq ft per gallon. A 12 × 12 ft bedroom needs about 2 gallons plus a quart.
Part of our guide: Interior House Paint Ideas: Color Schemes & Room Paint Design
Key takeaways
- One gallon of interior paint covers about 350–400 sq ft (33–37 m²) per coat on smooth, primed walls, and 250–300 sq ft (23–28 m²) on textured or porous surfaces
- Paint needed = wall area minus doors and windows, times number of coats, divided by coverage per gallon
- A quart covers roughly 75–100 sq ft (7–9 m²) per coat, so four quarts cost more than one gallon for the same paint
- Buy about 10 percent extra and keep a labeled quart for touch-ups from the same batch
For most rooms, you need about one gallon of paint for every 350–400 sq ft (33–37 m²) of wall per coat. Measure the wall area, subtract doors and windows, multiply by two coats and divide by 350. A typical 12 × 12 ft (3.7 × 3.7 m) bedroom with 8 ft walls needs about 2 gallons plus a quart for the walls.
- Gallon of paint coverage: 350–400 sq ft per coat on smooth primed walls; 250–300 sq ft on texture, brick or fresh drywall.
- Quart coverage: about 75–100 sq ft (7–9 m²) per coat.
- Coats: plan two coats for walls; three or a primer for big color changes.
- Metric shortcut: about 9–10 m² per liter per coat on smooth walls.
- Extra: add about 10 percent for waste and touch-ups.
Paint quantity is the dullest part of any project in our interior painting ideas guide and the one that most often stops it halfway: run out on the last wall and the new can rarely matches perfectly. The math below avoids that.
How much paint do I need for a room?
To work out how much paint you need for a room, divide the paintable wall area by the coverage per gallon and multiply by the number of coats. The full formula is:
Gallons = (perimeter × wall height − doors − windows) × coats ÷ coverage per gallon
Use 21 sq ft (about 2 m²) for a standard 3 × 7 ft door and about 15 sq ft (1.4 m²) for an average window, or measure your own. Coverage of 350 sq ft per gallon is a sensible planning number for interior acrylic on smooth walls; using the higher 400 sq ft figure from the label leaves no margin for a rough roller or porous patches.
Example: a 12 × 14 ft room with 8 ft walls has a perimeter of 52 ft and 416 sq ft of wall. Subtract one door and two windows (51 sq ft) to get 365 sq ft. Two coats is 730 sq ft; 730 ÷ 350 is 2.1, so buy 2 gallons plus 1 quart, or 3 gallons if you want spare paint. If your room is an odd shape, our how to calculate square footage guide breaks L-shapes and sloped ceilings into simple rectangles.
How many square feet does a gallon of paint cover?
A gallon of paint covers about 350–400 sq ft (33–37 m²) per coat on smooth, previously painted or primed walls, and noticeably less on rough, porous or unprimed surfaces. The figure printed on the can is the best case, measured on a sealed, smooth panel.
How much does a gallon of paint cover in real rooms? The table gives the planning numbers we use for different products and surfaces.
| Product and surface | Coverage per gallon, per coat | Metric (per 3.78 L) | Notes |
|---|---|---|---|
| Interior acrylic, smooth painted walls | 350–400 sq ft | 33–37 m² | Standard planning figure |
| Interior acrylic, light texture (orange peel, knockdown) | 300–350 sq ft | 28–33 m² | Use a 1/2 in (13 mm) nap roller |
| Paint-and-primer on new drywall | 250–300 sq ft | 23–28 m² | Separate drywall primer is cheaper |
| Drywall or stain-blocking primer | 200–300 sq ft | 19–28 m² | Porous surfaces drink the first coat |
| Ceiling paint, flat | 350–400 sq ft | 33–37 m² | Popcorn texture: 150–250 sq ft |
| Trim and door enamel | 350–450 sq ft | 33–42 m² | Thinner coat, but brush loss |
| Exterior acrylic on siding | 250–350 sq ft | 23–33 m² | Rough-sawn wood near the low end |
| Masonry, stucco or brick | 100–200 sq ft | 9–19 m² | Very porous; back-roll or spray |
So how many sq ft does a gallon of paint cover for a normal bedroom repaint in a similar color? Plan on 350. For a fresh new-build with bare drywall, plan on 250–300 for the first coat and 350 for the second.
How much does a quart of paint cover?
A quart of paint covers about 75–100 sq ft (7–9 m²) per coat, one quarter of a gallon. That is enough for a small accent wall in one coat, a powder room ceiling, or a set of interior doors on one side.
How many square feet does a quart of paint cover in practice? A 10 ft (3 m) wide accent wall 8 ft (2.4 m) high is 80 sq ft, so one quart per coat and two quarts for two coats. Quarts usually cost 40–60 percent of a gallon, so once you need three quarts, a gallon is cheaper. Buy quarts for samples, touch-up stock and cabinet or furniture projects, not whole rooms.
How to calculate paint for your walls step by step
Calculate paint by measuring each wall, subtracting openings, and multiplying by coats before dividing by coverage. This takes about ten minutes per room with a tape or laser measure:
- Measure the perimeter. Add the length of every wall in feet (or meters), measured at baseboard height.
- Measure the wall height. Floor to ceiling, ignoring the baseboard and crown; 8, 9 and 10 ft (2.4, 2.7 and 3 m) are the common US heights.
- Multiply. Perimeter × height gives the gross wall area.
- Subtract openings. About 21 sq ft per door, 15 sq ft per window, plus built-ins, tiled areas and fireplace surrounds.
- Multiply by coats. Two for a similar color, three or primer plus two for a large change.
- Divide by coverage. 350 sq ft per gallon for smooth walls, 300 for texture, 250 for bare drywall.
- Round up and add 10 percent. Convert the remainder to quarts and round up to whole cans.
If you would rather skip the arithmetic, a paint calculator or paint coverage calculator does exactly these steps. Ours lets you enter each wall, openings and coats, and returns gallons and quarts.
Paint needed by room size: a quick chart
The fastest way to estimate paint is to match your room to a similar size; most bedrooms need 2 gallons and most living rooms need 3 for two coats on the walls. The figures below assume two coats at 350 sq ft per gallon, standard doors and windows, and smooth painted walls.
| Room (ceiling height) | Net wall area | Wall paint, 2 coats | Ceiling paint, 2 coats |
|---|---|---|---|
| 5 × 8 ft bathroom (8 ft) / 1.5 × 2.4 m | about 175 sq ft (16 m²) | 1 gallon | 1 quart |
| 10 × 10 ft bedroom (8 ft) / 3 × 3 m | about 285 sq ft (26 m²) | 2 gallons | 2–3 quarts |
| 12 × 12 ft bedroom (8 ft) / 3.7 × 3.7 m | about 350 sq ft (32 m²) | 2 gallons + 1 quart | 1 gallon |
| 12 × 16 ft living room (9 ft) / 3.7 × 4.9 m | about 455 sq ft (42 m²) | 3 gallons | 1 gallon + 1 quart |
| 14 × 18 ft living room (9 ft) / 4.3 × 5.5 m | about 510 sq ft (47 m²) | 3 gallons + 1 quart | 1.5–2 gallons |
| 20 × 20 ft open plan (9 ft) / 6 × 6 m | about 620 sq ft (58 m²) | 4 gallons | 2.5 gallons |
A whole 2,000 sq ft (186 m²) house interior, walls only, typically takes 15–20 gallons for two coats; add 5–8 gallons for ceilings and 2–4 for trim and doors.
How much paint for ceilings, trim and doors?
Ceilings need roughly the same coverage per gallon as walls, but trim and doors are measured differently and usually need far less paint than people buy. Treat each as its own quantity, because each uses a different product and sheen.
- Ceilings: length × width of the room, two coats, at 350 sq ft per gallon. A 12 × 12 ft ceiling (144 sq ft) needs 1 gallon for two coats.
- Baseboard and casing: one gallon of trim enamel typically covers the baseboards, casings and window trim of 4–6 average rooms for two coats.
- Interior doors: about 1 quart covers both sides of 2–3 flat slab doors for two coats; paneled doors use a little more.
- Cabinets: a typical 10 × 10 ft kitchen uses 1–1.5 gallons of cabinet enamel plus 1 gallon of bonding primer.
Our ceiling and trim paint guide covers which white and which sheen to use for each.
What changes paint coverage?
Surface texture, porosity, the size of the color change, the application tool and the paint's own solids content change paint coverage more than anything printed on the label. Here is how much each typically moves the number:
- Texture: orange peel and knockdown cut coverage 10–20 percent; heavy or popcorn texture can halve it.
- Porosity: fresh drywall compound, bare plaster and masonry absorb the first coat; prime them.
- Color change: dark to light, or deep reds and yellows, may need a tinted primer plus two coats, or three coats.
- Application: spraying wastes 20–40 percent in overspray; a roller is the most efficient method.
- Paint quality: higher-solids paints hide better per coat, which can save a third coat on strong colors.
- Sheen: glossier paints show thin spots, so they often need a full second coat even over a similar color; our eggshell vs satin guide explains which sheen hides most.
How much paint per square foot?
Paint per square foot is roughly 0.0025–0.003 gallons (about 0.32–0.37 fl oz, or 10–11 ml) per coat on smooth walls. Turned around, the usual square feet per gallon of paint is 350–400, which is the figure most people actually use.
Gallons of paint per square foot is useful for budgeting large commercial or multi-unit projects: multiply total wall area by 0.003 and by the number of coats for a conservative gallon count, then compare the cost of 1-gallon cans against 5-gallon pails, which are typically 10–20 percent cheaper per gallon.
Mistakes we see when buying paint
The mistake we see most often is buying from the can's best-case coverage, then running short on the final wall and having to open a can from a different batch. The others:
- Forgetting primer. New drywall, patched walls and big color changes need it; it is cheaper than a third coat.
- Buying quarts for rooms. Three or more quarts almost always cost more than a gallon.
- Not boxing cans. Mix all gallons of one color together in a larger bucket so any tint variation is averaged out.
- Throwing away leftovers. Keep a labeled quart with room name, color code and date for touch-ups.
Our verdict: plan at 350 sq ft per gallon, two coats, plus 10 percent, and you will rarely be short or left with more than one spare quart. That simple rule answers how much paint do I need for nearly every room in a house.
Want the exact number for your rooms? Enter your walls, doors and windows in our free paint calculator and it returns gallons and quarts for walls, ceiling and trim in seconds.
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Frequently asked questions
How much paint do I need for a 12 × 12 room?
A 12 × 12 ft (3.7 × 3.7 m) room with 8 ft walls, one door and one window needs about 2 gallons plus a quart of paint for two coats on the walls, based on 350 sq ft per gallon. The ceiling needs roughly 1 more gallon for two coats. Add primer if the walls are new drywall or you are making a big color change.
How many square feet does a gallon of paint cover?
A gallon of paint covers about 350–400 sq ft (33–37 m²) per coat on smooth, previously painted walls. Textured walls drop to about 300–350 sq ft, new drywall to 250–300, and brick or stucco to 100–200. Plan at the lower end of the range so you do not run short on the last wall.
How much does a quart of paint cover?
A quart of paint covers roughly 75–100 sq ft (7–9 m²) per coat, a quarter of a gallon's coverage. That is enough for one coat on a small accent wall, a powder room ceiling or a few doors. If you need three quarts or more, buy a gallon instead, because it is usually cheaper.
Do I need two coats of paint?
Yes, two coats are standard for walls, even when the can says one-coat coverage. The second coat evens out sheen, hides roller marks and gives full color depth and durability. Use primer plus two coats on new drywall, patched areas and dramatic color changes, especially when going from dark to light.
How much paint do I need for a whole house interior?
A 2,000 sq ft (186 m²) house interior typically needs 15–20 gallons of wall paint for two coats, plus 5–8 gallons for ceilings and 2–4 gallons of trim enamel. Larger houses scale roughly in proportion. Measure each room or use a paint calculator for an exact figure, and buy in 5-gallon pails for main colors.
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