Calculators / Paint
Paint Calculator
To calculate paint, enter the total wall length, height, and number of coats; this tool returns the gallons needed and a cost estimate. One gallon covers about 350 square feet per coat.
Real math, not AI guesses.
You need
2 gallons
Estimated cost
~$70
- Wall area
- 320 sq ft
- Coats
- 2
- Gallons (350 sq ft/coat)
- 2
Estimate only — actual quantities and prices vary by region and supplier. Verify with a professional before purchasing. Default price is a national average (as of 2026-06); edit it to match your supplier.
How to calculate paint
The formula: gallons = ceil( wall area × coats ÷ 350 )
- Add up the length of all walls and multiply by the wall height for total area.
- Subtract large openings like doors and windows if you want a tighter estimate.
- Multiply area by the number of coats.
- Divide by 350 (coverage of one gallon) and round up.
Prices shown are national averages (as of 2026-06) and vary by region, brand, and supplier. They are estimates, not quotes.
How much does it cost to paint a room?
Interior paint costs about $25–$60 per gallon, and one gallon covers roughly 350 sq ft per coat. In materials, a typical room runs $50–$150 including paint, primer, tape, and rollers. Hiring a pro usually costs $300–$800 per room, or about $2–$6 per square foot of floor area, including labor and prep. For an average 12×12 bedroom, expect roughly $350–$700 painted by a pro.
What drives the cost
- Paint grade: premium and specialty (kitchen/bath, low-VOC) paints cost more per gallon.
- Coats and color change: dark-to-light needs primer plus two coats.
- Prep: patching, sanding, and priming bare or damaged walls add labor.
- Ceilings, trim, and high walls add time beyond the wall area.
- Two coats is standard — one gallon does about 175 sq ft over two coats.
DIY vs. hiring a pro
Painting is the most DIY-friendly project on this site — a room's worth of paint and supplies is usually under $150, and the skill is mostly patience with cutting in and prep. Hiring out mainly buys speed, clean lines, and skipping the prep. For high ceilings, lots of trim, or a whole house, a pro crew is faster; for a single room, DIY saves most of the cost. If you hire, confirm whether prep and primer are included.
Installed and labor figures are national-average ranges, not quotes — get a few local estimates for your project.
Paint FAQ
How much paint do I need for a room?+
A room with 40 ft of wall at 8 ft high is 320 sq ft. For two coats that is 640 sq ft, or about 2 gallons at 350 sq ft per gallon.
Does one gallon of paint do two coats?+
One gallon covers about 350 sq ft for a single coat. For two coats, plan on roughly one gallon per 175 sq ft of wall.
How much does it cost to paint a 12×12 room?+
In materials, a 12×12 room is about $50–$150 in paint and supplies. Hiring a pro typically runs $350–$700 for the same room, since labor and prep are most of the cost.
Is it cheaper to paint a room yourself?+
Much cheaper — paint and supplies for one room are usually under $150, while hiring a pro is several hundred. DIY trades your time and prep work for the labor savings.