How much paint do I need for a 12x14 room?

A 12x14 room with 8 ft ceilings has 416 sq ft of wall. Minus 2 doors and 2 windows (70 sq ft) leaves 346 sq ft; two coats is 692 sq ft. At typical 375 sq ft per gallon, that is 1.85 gallons — buy 2.

How many square feet does a gallon of paint cover?

Most interior latex paints cover 350-400 sq ft per gallon per coat — the calculator uses 375 as the default and lets you change it. Primers cover less (200-300), textured walls eat more, and a dramatic color change can add a coat.

Should I subtract doors and windows from the paint area?

Yes — deduct about 20 sq ft per door and 15 sq ft per window. You will still paint the door edges and trim with something, but the wall paint math is tighter and saves you a quart or two per room, which adds up over a whole house.

Do I need two coats of paint?

Usually yes for anything other than repainting the same color in good condition. Two coats even out absorption, hide the old color, and most manufacturer warranties assume them. Dark over light or light over dark: two coats minimum, sometimes a tinted primer first.

Paint Calculator

Wall area minus doors and windows, times your coats — gallons and quarts, with the deductions the one-box tools skip.

The short answer

Formula. Gallons = (wall area − 20 sq ft per door − 15 sq ft per window) × coats ÷ coverage per gallon (interior latex spreads about 375 sq ft), rounded up to buy.

Example. A 12×14×8-ft room with 2 doors and 2 windows painted in 2 coats needs 1.85 gallons — buy 2.

Room & paint

Room length (ft)

Room width (ft)

Ceiling height (ft)

Doors

−20 sq ft each.

Windows

−15 sq ft each.

Coats

Coverage per gallon (sq ft)

Interior latex: 350–400.

Ceiling too?

How this calculator works

Paint need is coverage math: area to paint, times coats, divided by how far a gallon spreads. Wall area for a rectangular room is the perimeter (2 × (length + width)) times ceiling height — the 12 × 14 default room is 52 ft around × 8 ft = 416 sq ft. Then the deductions, which is where this calculator earns its keep: a standard door is about 20 sq ft and a typical window 15, and subtracting them means you are not buying paint for glass you will mask anyway. 416 − 40 − 30 = 346 sq ft of actual wall.

Coats multiply, coverage divides. Two coats on 346 sq ft is 692 sq ft of spreading; at the default 375 sq ft per gallon that is 1.85 gallons, and since paint is sold in gallons (and quarts), the readout tells you 2 gallons — with the quart-equivalent shown, because a 7 × 10 touch-up room famously needs "a quart and a prayer," not a gallon. The coverage default of 375 sits mid-range of the 350–400 most interior latex labels claim; heavy textures (orange peel, knockdown) push consumption up 10–20%, smooth new drywall with primer drinks less, and the label on YOUR can always outranks a default.

What this room-shape math deliberately leaves out, and how to add it back: measure oddly shaped walls (stairwells, gables, soffits) as height × width each and sum them, then use the same division. Trim, baseboards and doors are painted at roughly 32 linear ft of trim per gallon per coat — one quart usually does a room's casings. Ceiling white, if you include the ceiling, spreads further than wall paint on flat drywall (400+ per gallon). And the old painter's rule the arithmetic proves: for a whole house in one color, buy the 5-gallon pail — per-gallon pricing punishes room-by-room buying by 20–30%.

Sources & review date

Coverage of 350–400 sq ft per gallon is the typical manufacturer spread rate for interior latex; the page default is 375 and editable.

Last reviewed: October 2026. Numbers that drift (fees, prices, densities) are editable inputs on this page.

Paint FAQs

Will one gallon of paint cover my room?

A gallon per coat covers about 375 sq ft — an 8 × 10 room (256 sq ft of wall) gets one full coat and most of a second from a single gallon. Bigger rooms, or any two-coat job over 190 sq ft of wall, need two gallons.

Does paint color change how much I need?

Coverage per gallon is roughly the same, but hiding power is not: deep reds and saturated navies over light walls, or white over dark, may need three coats or a tinted primer — add a coat in the calculator and buy accordingly.

How do I paint around a big window or sliding door?

Just deduct it: a sliding patio door is roughly 40 sq ft — count it as two doors. The deductions box exists precisely so your gallon count matches your actual wall, not the room's bounding box.

Do I count closets?

If you are painting inside them, yes: measure the closet's walls and add them (a standard reach-in closet adds 60–80 sq ft). If not, close the door and skip it.

Assumptions this tool makes: the room is a rectangle with vertical walls; door and window deductions are 20 and 15 sq ft each; coverage per gallon is as entered (default 375); "gallons to buy" rounds up to whole gallons after showing the exact figure. Estimates are for planning — check the coverage figure on your paint's label.