Construction

Paint Calculator

Calculate gallons of paint, quarts, and costs for your painting project

Quick Answer:A 15x12 ft room with 8 ft ceilings and 2 coats of paint requires approximately 2.3 gallons of paint in 2026 (after subtracting 40 sq ft of openings). At $35-55 per gallon, expect to spend $80-125 on quality interior paint.

Room & Paint Details

Room Length (ft)

Room Width (ft)

Wall Height (ft)

Openings (sq ft)

Number of Coats

Coverage (sq ft/gal)

Gallons Needed

Calculating... gallons

Wall Area

Quarts Needed

Estimated Cost

Coverage per Coat

Visual Comparison

Wall Area --

Gallons --

Cost (mid-range) --

Expert Insight 2026 Pro Tip

In 2026, premium paint with built-in primer often provides better one-coat coverage, potentially saving you the cost of a second gallon. Textured walls and bare drywall absorb 15-25% more paint than smooth, previously painted surfaces -- adjust your coverage rate down to 275-300 sq ft per gallon in these cases. Buy all paint at once from the same batch to ensure color consistency, and keep at least one quart for touch-ups. For best results, maintain a wet edge and paint in consistent light conditions.

Frequently Asked Questions About Paint

How do I calculate how much paint I need for a room?

To calculate paint for a room, first find the total wall area by multiplying the room perimeter (2 times length plus 2 times width) by the ceiling height. Subtract the area of doors (about 21 sq ft each) and windows (about 15 sq ft each). Multiply the net area by the number of coats (usually 2), then divide by the paint coverage rate (typically 350 sq ft per gallon for standard latex paint). For a 15x12 ft room with 8-foot ceilings, the wall area is 432 sq ft. After subtracting 40 sq ft of openings, two coats require about 2.3 gallons of paint.

How many coats of paint do I need?

Most interior painting jobs require 2 coats for proper coverage and color consistency. However, some situations may require more or fewer coats. One coat may suffice when repainting with the same or very similar color using high-quality paint with built-in primer. Three coats are recommended when covering dark colors with light paint, painting over bare drywall or new plaster, or using certain red and deep-tone colors that have lower pigment opacity. Always apply a primer coat first on new or patched surfaces, as it improves adhesion and reduces the total number of finish coats needed.

How much does interior paint cost in 2026?

In 2026, interior paint ranges from $25-70 per gallon depending on quality and brand. Budget-friendly options like basic latex paint cost $25-35 per gallon and work well for ceilings and low-traffic areas. Mid-range paints from brands like Behr or Valspar cost $35-50 per gallon, offering good coverage and washability. Premium paints from Benjamin Moore or Sherwin-Williams range from $50-70 per gallon but provide superior coverage, durability, and often one-coat capabilities. Professional painters charge $2-6 per square foot for labor, which includes surface prep, priming, and two coats.