Do I need one coat or two coats of paint?

Two coats are almost always recommended for a durable, even finish. One coat may be sufficient when painting a similar color over a well-primed surface. Going from dark to light, painting new drywall, or making a significant color change will require at least two coats and may benefit from a primer coat first.

Do I need to paint the ceiling a different amount?

Ceiling paint typically covers 300 to 350 sq ft per gallon due to the texture of most ceilings. Flat paint is standard for ceilings. Calculate ceiling square footage separately since it often requires a different paint product than your walls.

Paint Coverage Calculator — Gallons & Coats

Free Estimator

Paint Coverage Calculator

Add your walls and ceiling, subtract door and window openings, and choose your surface type. The calculator handles the rest.

Walls

Length (ft)

Height (ft)

Count

Ceiling (optional)

Length (ft)

Width (ft)

Deductions

Standard door ≈ 21 sq ft · Standard window ≈ 15 sq ft

Doors

Windows

Custom (sq ft)

Paint Options

Surface type

Number of coats

Waste factor

Paint price ($/gallon, optional)

Your Paint Estimate

Gallons Needed

—

2 coats + waste

Quarts (alt.)

—

quarts total

Paintable Area

—

sq ft (after deductions)

Per Coat

—

gallons per coat

Est. Cost

—

paint material only

Coverage Rate

—

sq ft per gallon

Paint Coverage by Surface Type

Surface	Coverage (sq ft/gal)	Notes
Smooth, primed walls	380–400	Best case scenario. Clean, sealed surface with primer coat already applied.
Standard interior walls	350–380	Typical repaint on previously painted walls in good condition.
Textured / orange peel	300–350	Texture absorbs more paint. Orange peel and knockdown finishes fall here.
New / bare drywall	200–250	Absorbs heavily on first coat. Always prime bare drywall before painting.
Ceiling (flat paint)	350–380	Flat paint is standard for ceilings. Similar coverage to smooth walls.
Masonry / brick	150–200	Very porous. First coat is essentially a primer coat. Expect 2–3 coats minimum.

New drywall — always prime first Painting directly on bare drywall without primer wastes paint and produces an uneven finish. The paper face of drywall absorbs paint unevenly, leaving a blotchy appearance called "flashing." A single coat of drywall primer seals the surface and cuts total paint consumption by 30–40%.

One Coat vs. Two Coats

Two coats are the professional standard for any interior paint job. One coat is acceptable only when repainting a very similar color over a well-sealed surface. For color changes, new drywall, or any situation where you want a durable finish that holds up to cleaning and touch-ups, two coats is the correct answer.

If you're going from a dark color to a light one, plan for three coats or use a tinted primer to reduce the number of paint coats needed.

Frequently Asked Questions

How much paint do I need for a room?

Add up all wall square footage, subtract doors and windows, divide by 350–400 (the coverage rate per gallon), and multiply by the number of coats. Add 10% for waste. This calculator does all of that automatically.

How many square feet does a gallon of paint cover?

Most interior paints cover 350 to 400 square feet per gallon on smooth, previously painted surfaces. Textured walls, bare drywall, and porous surfaces can drop coverage to 200–300 sq ft per gallon. Check your specific paint's label.

Do I need one coat or two coats?

Two coats are almost always recommended for a durable, even finish. One coat works only when repainting a similar color over a primed surface. For color changes, dark-to-light transitions, or new drywall, plan for two coats minimum.

How much extra paint should I buy?

Buy 10% more than your calculation indicates — for waste, roller loading, and future touch-ups. For custom-mixed colors this is especially important, as matching the exact formula later can be difficult.

Should I paint the ceiling separately?

Yes. Ceiling paint is a different product (flat sheen, often thicker) and covers at a slightly different rate. Calculate ceiling square footage separately and buy ceiling paint as a distinct line item from your wall paint.

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Paint Coverage Calculator —Gallons & Coats

Paint Coverage by Surface Type

One Coat vs. Two Coats

Frequently Asked Questions

Deep guides for every challenge

Paint Coverage Calculator —
Gallons & Coats