Paint Calculator | EasyHomeCalcs

Paint Gallon Calculator

Estimate the amount of paint gallons needed based on wall dimensions and number of coats.

Total Room/Wall Length (Feet)

Wall Height (Feet)

Number of Coats

Estimated Material:

Total Square Footage: 0 sq ft

Paint Required: 0 Gallon(s)

How to Calculate Wall Paint

Multiply the total length of all walls by the ceiling height to get the gross surface square footage. A standard single gallon of premium interior paint typically covers around 350 to 400 square feet of flat wall surface area.

Important DIY Painting Tips

Deduct Openings: For optimal precision, subtract 21 sq ft for each standard door frame and 15 sq ft for each medium window frame from your total calculation.
Primer Requirements: Raw drywall or heavily repaired surfaces absorb paint rapidly. Always apply a dedicated primer coat first to prevent wasting expensive topcoats.
Sheen Matters: Flat and matte finishes hide wall imperfections but are harder to clean. Satin and eggshell hold up better in high-traffic rooms like kitchens and hallways.

Choosing Between One and Two Coats

A single coat is rarely enough for a true, even color, especially over a different existing color or bare drywall. Two coats are standard practice for most interior projects and are already factored into this calculator's default setting. Dramatic color changes, such as painting over a dark wall with a light color, may require a tinted primer or a third coat for full coverage.

Frequently Asked Questions (FAQs)

Q1: How much wall area does one gallon of paint cover?

A: A standard gallon of interior paint covers roughly 350 to 400 square feet per coat on smooth, primed drywall. Textured surfaces reduce coverage since more paint gets absorbed into the texture.

Q2: Should I buy extra paint beyond the calculated amount?

A: Yes, a small buffer (roughly half a gallon) is wise for touch-ups down the road and to cover any underestimation from wall texture or an uneven surface.