Interior paint calculator
Estimate how many gallons of interior paint you need for walls, ceiling, trim, and doors. Enter the room's dimensions and openings and the calculator returns the gallons plus a real per-gallon price for any of 15 brands, so you see the paint cost before you shop. For the full paint-plus-labor total, use thecost calculator.
The math behind the estimate
Wall area = perimeter (2 × length + 2 × width) × ceiling height. We subtract 21 sq ft per door and 15 sq ft per window. The result is multiplied by the number of coats and divided by the paint's coverage rate (Kompozit ONE covers ~388 sq ft per gallon). The final number is rounded up to the nearest quart, since paint sells in 1-qt increments.
Coverage of 350 to 400 square feet per gallon is the published number on most premium interior paints, and it assumes smooth, primed drywall. Rough texture, deep accent colors, and fresh unprimed board all pull the real-world figure lower, so the calculator leans on the conservative end and lets you add a touch-up buffer.
When to use 1 vs. 2 vs. 3 coats
Coats are the single biggest lever on how much paint you buy — going from one to two coats doubles the gallons. Two coats is the right default for almost every job; one is only for a true same-color refresh, and three is reserved for the colors that physically can't hide in two.
- 1 coat: repaint in the exact same color, freshening up rather than changing.
- 2 coats: default for most jobs, including same-family color changes such as beige to tan.
- 3 coats: dark over light, vivid reds and yellows that always need extra hide, or any color shift over an unprimed surface.
Texture, primer, and finish pull the number around
Two things blow up a paint estimate: surface texture and color jumps. Knockdown or orange-peel walls can cut coverage by 20 to 50 percent versus smooth drywall, and a strong color change can add a whole coat. A tinted primer fixes both at once — it seals porous surfaces and shifts the base toward the new color so the topcoat hides in fewer passes. Trim is a separate buy, usually a single quart of semi-gloss or satin per room, because the finish differs from the walls.
Paint cost by brand
Paint cost is gallons × price per gallon, and coverage is similar (about 350 to 400 sq ft per gallon) across the major interior lines, so the price tier is what moves your bill. These are current per-gallon prices for the brands the calculator can price for you:
| Brand & line | Price / gal | Coverage |
|---|---|---|
| Backdrop Interior Standard | ~$59/gal | 400 sq ft/gal |
| Behr Marquee | ~$52/gal | 400 sq ft/gal |
| Behr Dynasty | ~$65/gal | 400 sq ft/gal |
| Behr Ultra | ~$45/gal | 400 sq ft/gal |
| Behr Premium Plus | ~$33/gal | 400 sq ft/gal |
| Benjamin Moore Aura | ~$80/gal | 400 sq ft/gal |
| Benjamin Moore Regal Select | ~$64/gal | 400 sq ft/gal |
| Benjamin Moore Ben | ~$45/gal | 400 sq ft/gal |
| Benjamin Moore Ultra Spec 500 | ~$40/gal | 400 sq ft/gal |
| C2 Paint LUXE | ~$82/gal | 400 sq ft/gal |
| C2 Paint Studio | ~$70/gal | 400 sq ft/gal |
| C2 Paint LoVo | ~$65/gal | 400 sq ft/gal |
| Clare Wall Paint | ~$54/gal | 400 sq ft/gal |
| Diamond Vogel Avalon | ~$48/gal | 400 sq ft/gal |
| Diamond Vogel Assure | ~$36/gal | 400 sq ft/gal |
| Diamond Vogel Artistry | ~$42/gal | 400 sq ft/gal |
| Dunn-Edwards Everest | ~$67/gal | 400 sq ft/gal |
| Dunn-Edwards Suprema | ~$60/gal | 400 sq ft/gal |
| Dutch Boy Platinum Plus | ~$38/gal | 400 sq ft/gal |
| Dutch Boy Dura Clean | ~$35/gal | 400 sq ft/gal |
| Dutch Boy Forever | ~$30/gal | 400 sq ft/gal |
| Dutch Boy Pristine | ~$46/gal | 400 sq ft/gal |
| Farrow & Ball Estate Emulsion | ~$120/gal | 400 sq ft/gal |
| Farrow & Ball Modern Emulsion | ~$140/gal | 400 sq ft/gal |
| Farrow & Ball Dead Flat | ~$130/gal | 400 sq ft/gal |
| Glidden Diamond | ~$37/gal | 400 sq ft/gal |
| Glidden Premium | ~$22/gal | 350 sq ft/gal |
| Glidden Essentials | ~$18/gal | 350 sq ft/gal |
| Glidden High Endurance Plus | ~$28/gal | 400 sq ft/gal |
| HGTV Home by Sherwin-Williams Infinity | ~$46/gal | 400 sq ft/gal |
| HGTV Home by Sherwin-Williams Showcase | ~$38/gal | 400 sq ft/gal |
| HGTV Home by Sherwin-Williams Ovation Plus | ~$33/gal | 400 sq ft/gal |
| Kompozit ONE | ~$40/gal | 388 sq ft/gal |
| Kompozit PRO | ~$52/gal | 388 sq ft/gal |
| Kompozit NEO | ~$65/gal | 425 sq ft/gal |
| Magnolia Home Interior | ~$50/gal | 400 sq ft/gal |
| Portola Paints New Standard | ~$80/gal | 400 sq ft/gal |
| PPG Timeless | ~$45/gal | 400 sq ft/gal |
| PPG Diamond | ~$36/gal | 400 sq ft/gal |
| PPG Manor Hall | ~$55/gal | 400 sq ft/gal |
| PPG Speedhide | ~$28/gal | 400 sq ft/gal |
| PPG UltraLast | ~$48/gal | 400 sq ft/gal |
| Rodda Horizon Interior | ~$52/gal | 400 sq ft/gal |
| Rodda RESIST-X | ~$58/gal | 400 sq ft/gal |
| Sherwin-Williams Emerald | ~$74/gal | 400 sq ft/gal |
| Sherwin-Williams Duration Home | ~$70/gal | 400 sq ft/gal |
| Sherwin-Williams Cashmere | ~$60/gal | 400 sq ft/gal |
| Sherwin-Williams SuperPaint | ~$60/gal | 400 sq ft/gal |
| Sherwin-Williams ProMar 200 | ~$45/gal | 400 sq ft/gal |
| Valspar Reserve | ~$52/gal | 400 sq ft/gal |
| Valspar Signature | ~$40/gal | 400 sq ft/gal |
| Valspar Simplicity | ~$22/gal | 350 sq ft/gal |
Run the calculator, pick a brand and line in the result panel, and it multiplies your gallons by that product's price for an exact paint cost. Prices are US averages and vary by region and retailer.
What it costs to paint a room
Doing it yourself, a standard 12-by-14-foot room is cheap: about $50 to $150 in paint (one to two gallons of a $40 to $70 product) plus $50 to $100 in supplies — rollers, brushes, tape, trays, and drop cloths. That is your whole cost if you bring the labor.
Hiring a painter changes the math completely. Most homeowners pay $400 to $1,600 per room, around $1,100 on average, because labor is 75 to 95 percent of an interior bill — prep, cutting in, and cleanup eat the hours. Pros generally charge $2 to $6 per square foot of floor area. For a full breakdown with labor by region, use thepaint cost calculator.