Paint Cost Calculator

Paint Cost formula

Area = 2 x (Length + Width) x Height - (Doors x 20) - (Windows x 15)  (+ Length x Width if the ceiling is included)
Gallons to buy = round up (Area x Coats / Coverage per gallon)
Paint cost = Gallons x price per gallon;  Primer cost = round up (Area / 300) x $30
Total = Paint + Primer + (Labor rate x Area);  Cost per sq ft = Total / Area

Worked example

A 14 x 16 ft living room with 9 ft ceilings, two doors and three windows, painted with $40 per gallon paint: 2 x 30 x 9 = 540 sq ft, minus 40 for doors and 45 for windows = 455 sq ft of wall. Two coats at 350 sq ft per gallon: 455 x 2 / 350 = 2.6 gallons, so buy 3 gallons for 3 x $40 = $120. One coat of primer: 455 / 300 = 1.52, so 2 gallons at $30 = $60. DIY materials come to $180, or $0.40 per sq ft.

Hiring a painter at $3 per sq ft adds 455 x $3 = $1,365 in labor, for a total of $1,545, or $3.40 per sq ft of wall.

Quick reference

How to estimate the cost of painting a room

Start with the wall area: perimeter times ceiling height, less about 20 sq ft per door and 15 per window. Multiply by the number of coats, divide by the coverage on the can, and round up to whole gallons, because paint is sold by the gallon and quart, not the ounce. Multiply by the price per gallon for the paint cost. Add a gallon of primer for every 300 sq ft if the walls are bare, patched or changing from dark to light.

Budget separately for supplies if you do not already own them: rollers, brushes, tape, drop cloths and a tray typically add a few tens of dollars for a first room and much less for each room after. Ceiling paint and trim paint are usually different products, so price them on their own.

DIY vs hiring a painter

Painting is one of the few jobs where doing it yourself saves most of the cost. Materials for a bedroom run under $150; a professional bid for the same room can be $500 or more because labor dominates. Pros earn their fee on prep, cut lines, high ceilings and speed, so the gap narrows on rooms with lots of trim, damaged walls or stairwells.

When you get bids, ask whether paint is included, how many coats, and whether ceilings and trim are extra. Many painters quote by the square foot of wall, some by the room or by the hour. If a quote already includes paint, set the paint price here to 0 and enter the quoted rate as labor to compare it against buying the paint yourself.

Key facts

• Labor is the largest share of a professional paint job; the paint itself is usually 15 to 25% of the total, so a $90 material estimate often becomes a $400 to $600 quote for one room.
• Professional painters charge about $2 to $6 per sq ft of wall area, and labor is usually the largest share of the bill.
• Interior paint costs about $20 to $70 per gallon; premium paint-and-primer products cost more but often cover in fewer coats.
• One gallon covers about 350 to 400 sq ft per coat, so a 12 x 12 ft room takes about 2 gallons for two coats on the walls.
• Primer runs about $20 to $40 per gallon and covers 250 to 300 sq ft; bare drywall, patches and dark-to-light color changes need it.

Frequently asked questions

Sources and references

• •Paint calculator: paint and primer coverage per gallon (Sherwin-Williams)
• •KILZ 2 All-Purpose Primer product page (KILZ)
• •Painters, Construction and Maintenance, Occupational Outlook Handbook (U.S. Bureau of Labor Statistics)