Free Paint Calculator: How Many Gallons?
Enter the wall length and height, the ceiling area and the trim. Doors and windows come out of the wall area. You’ll get paint by the gallon and the 5-gallon bucket for each surface, primer if you need it, and caulk and tape. These are the same rules LaraKey’s takeoff calculator uses.
Paint to buy
Estimates only. Measure on site and check with your supplier before you order.
How to calculate paint
Wall area = Wall length × Height − (Doors × 20 sq ft) − (Windows × 15 sq ft)
Wall or ceiling gallons = Area × Coats ÷ 350 sq ft per gallon + waste
Trim gallons = Trim length × Coats ÷ 400 ft per gallon + waste
Primer gallons = (Walls + Ceilings) ÷ 300 sq ft per gallon + waste
Buckets: every 5 gallons is a bucket; 4 or more gallons left over becomes another bucket.
Caulk = (Trim + 17 ft per door or window) ÷ 30 ft per tube. Tape = (Wall length × 2 + 17 ft per opening) ÷ 180 ft per roll.
Examples
A 12 × 14 ft bedroom, two coats
52 ft × 8 ft = 416 sq ft, less 1 door and 2 windows = 366 sq ft. × 2 coats ÷ 350 + 10% = 2.3 → 3 gallons for walls. The 168 sq ft ceiling needs 2 gallons.
A whole first floor
240 ft of wall × 9 ft = 2,160 sq ft, less 6 doors and 12 windows = 1,860 sq ft. × 2 coats ÷ 350 + 10% = 11.7 → 12 gallons = 2 buckets and 2 gallons.
Paint Calculator: common questions
How much does a gallon of paint cover?
About 350 sq ft per coat on smooth, primed walls. Rough or porous surfaces can drop that to 250 to 300.
How many coats of paint do I need?
Two coats is standard for walls, especially with a color change. One coat can work for a fresh coat of the same color.
When do I need primer?
On new drywall, patched areas, stains, big color changes and glossy surfaces. Check the Prime first box.
Should I buy 5-gallon buckets or gallons?
Buckets are cheaper per gallon and keep the color consistent on big jobs. The calculator switches to a bucket when 4 or more gallons are left over.
How much extra paint should I buy?
About 10% for touch-ups and spills. The calculator adds it for you.
How do I measure a room for paint?
Add up the length of all the walls and multiply by the height. Measure the ceiling as length × width. Count doors and windows.
How much trim paint do I need?
About one gallon per 400 linear feet of trim per coat.
Are these numbers exact?
They’re estimates based on common coverage rates. Check the coverage on the can and adjust for the surface.
Talk to a person who knows remodeling.
Looking for more free tools?
Drywall Calculator
Sheets for walls and ceilings, plus screws, tape, joint compound and corner bead.
Use calculatorConcrete Calculator
Cubic yards and 80 or 60 lb bags for slabs, footings, walls and post holes.
Use calculatorLabor Cost Calculator
Find what an hour of labor really costs after taxes, comp and time you can’t bill.
Use calculatorJob Pricing Calculator
Add up labor, materials, subs and overhead, set your profit, and get a bid price.
Use calculator