How much paint does this room need?
Enter the room and pick what you are painting. The calculator uses Sherwin-Williams' interior coverage rates and shows a range, in gallons and quarts. No prices, no signup.
01 Your room
0 gallons of paint
Trim, doors and cabinets take a separate enamel. Buy a little extra for touch-ups.
How the math works
Wall area is the distance around the room (twice the length plus twice the width) times the wall height, minus the doors and windows. The ceiling is length times width. Paint needed is that area times the number of coats, divided by how far a gallon spreads.
Sherwin-Williams' data sheets list 350 to 400 sq ft per gallon per coat for both Emerald Interior and SuperPaint Interior. The calculator shows the result at both ends, so you see the range instead of one number built on a guess. Primer uses 400 sq ft per gallon, the rate on Sherwin-Williams' ProMar 200 interior primer sheet. Results round up to whole quarts; four quarts make a gallon.
When to plan two coats or a primer
- New drywall: two coats of a self-priming paint, or one coat of primer and then the paint, per the Emerald and SuperPaint interior sheets.
- A drastic color change: the same sheets say a coat of primer helps the new color hide the old one.
- Water stains: they need a stain-blocking primer, not more paint. See water stains on the ceiling.
Questions
How far does a gallon of interior paint go?
Sherwin-Williams' data sheets for Emerald Interior and SuperPaint Interior both list 350 to 400 sq ft per gallon per coat. Rough, patched or very porous walls take more.
Do new drywall walls need primer?
Either a primer coat or two coats of a self-priming paint. The Emerald and SuperPaint interior sheets allow 2 coats of the paint itself on drywall, or 1 coat of primer first.
I am going from dark red to white. What changes?
Plan on a primer coat. Sherwin-Williams' interior data sheets say a drastic color change benefits from a coat of primer before the finish coats.
Sources
- Sherwin-Williams, Emerald Interior Acrylic Latex Satin, product data sheet (11/2023)
- Sherwin-Williams, SuperPaint Interior Latex Satin, product data sheet (8/2026)
- Sherwin-Williams, ProMar 200 Zero VOC Interior Latex Primer, product data sheet (2/2025)
- Sherwin-Williams, How much paint to buy
Painting the outside instead? Use the Florida exterior paint calculator. Rather have a room done for you? See interior painting across Sarasota and Manatee County, with free on-site estimates from our family-owned painting business.
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