Question 1

How many gallons of paint do I need for a 12×14 room?

Accepted Answer

A 12×14 room with 8-foot ceilings has roughly 416 sq ft of wall space. Subtract one door (21 sq ft) and two windows (30 sq ft) and you're painting about 365 sq ft. One coat takes just over a gallon at 350 sq ft/gallon coverage. For two coats, which is almost always the right call, you'll need around 2.1 gallons. Buy two gallons and a quart.

Question 2

What is the standard coverage rate for interior paint?

Accepted Answer

Most interior latex paints cover 350 to 400 square feet per gallon on a smooth, properly primed surface. We use 350 sq ft/gallon as a slightly conservative baseline so you don't come up short. Premium paints with higher solids content can hit 400+ sq ft/gallon. Check the label before you buy.

Question 3

Should I subtract doors and windows from my paint calculation?

Accepted Answer

Experienced painters do. A standard 3×7 door is about 21 sq ft; an average window runs around 15 sq ft. Those deductions add up fast in a room with multiple openings. The calculator handles this automatically. If you have large picture windows or oversized doors, bump up the count rather than trying to account for exact dimensions.

Question 4

How many coats of paint do I need?

Accepted Answer

Two coats is the baseline for most interior repaints. Going from dark to light, or painting over fresh drywall, typically takes three. One coat is only worth considering for touch-up work or when the new color is almost identical to what's already on the wall.

Question 5

Do I need to prime before painting?

Accepted Answer

Primer earns its place in a few specific situations: bare drywall, bold color changes, stain coverage, and freshly patched walls. A good primer can often drop a three-coat job down to two. If you're doing a same-color repaint on a clean, solid surface, skip it.

Question 6

Should I calculate the ceiling separately?

Accepted Answer

If you're using a different product for the ceiling, run a separate calculation. Ceiling paint is usually flat finish and often a different brand than your wall paint. Coverage rates are similar, but ceilings typically only need one coat unless you're going over a dark color.

Question 7

How much extra paint should I buy?

Accepted Answer

Plan on 10% more than your calculated amount. Roller waste, uneven first passes, and touch-ups after furniture gets moved back in all eat into what looks like enough on paper. More importantly: keep a labeled quart for future touch-ups. Matching a color years later without the original formula is a headache.

Question 8

How do I calculate paint for an open floor plan or irregular room?

Accepted Answer

For L-shaped rooms or open plans, measure each rectangular section separately and use the Add Room button to total them. For curved or vaulted walls, measure the actual surface area as best you can and enter it as a custom room. When in doubt, round up rather than down.

Paint Type	Coverage (sq ft/gal)	Best For
Budget latex / eggshell	300–350	Rental units, low-traffic rooms
Mid-grade latex	350–380	Most interior walls (our default)
Premium paint + primer	380–400	Repaints over similar color
Ceiling paint (flat)	350–400	Flat ceilings
Exterior paint	250–350	Varies widely by texture

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