Paint Calculator
Estimate paint gallons for walls and ceilings. Account for doors, windows, and multiple coats with customizable coverage per gallon for accurate project planning.
Complete Guide: Paint Calculator
Everything you need to know about using this tool effectively
This paint calculator tells you how many gallons of paint to buy based on the total surface area you need to cover, the number of coats you plan to apply, and the coverage rate of your chosen paint. Enter your wall dimensions and the calculator subtracts for doors and windows to give you a realistic material estimate.
An online home improvement tool that computes paint quantity for interior and exterior projects. It calculates total paintable area from room dimensions, accounts for doors and windows, factors in the number of coats, and divides by the paint coverage rate to determine how many gallons you need. It also supports primer calculations for new or patched surfaces.
Interior Room Painting
Estimate paint needed for a bedroom, living room, or kitchen by entering wall dimensions, door and window counts, and desired number of coats.
Whole House Renovation
Calculate total paint requirements for an entire home by summing room estimates and planning bulk purchases for better pricing.
Exterior House Painting
Measure exterior wall areas including gable ends to estimate paint needed for siding, trim, and accent areas.
Paint Budget Planning
Multiply the calculated gallons by the price per gallon to estimate your total paint cost before heading to the store.
Measure Your Walls
Use a tape measure to find the height and length of each wall you plan to paint. Multiply to get the area of each wall.
Enter Wall Dimensions
Input the total wall area or individual wall measurements into the calculator. Specify doors and windows to subtract from the area.
Set Coats and Coverage
Choose how many coats you will apply and enter the coverage rate listed on your paint can, typically 350 to 400 square feet per gallon.
Check Your Estimate
Review the total gallons needed. Round up to the nearest whole gallon since partial gallons are not typically sold.
Always buy one extra gallon beyond your estimate to have touch-up paint available for future repairs and scuffs.
Use a tinted primer when covering dark colors to reduce the number of topcoats needed and save on paint costs.
Paint coverage varies by surface texture. Rough surfaces like stucco absorb more paint and may require 15 to 20 percent extra.
Two thin coats provide better coverage and durability than one thick coat, even if the thick coat looks adequate after drying.
Stir paint thoroughly before use and strain it through a mesh screen if it has been sitting for several months.
How much paint do I need for one room?
A typical 10 by 12 foot room with 8 foot ceilings needs about 1 to 2 gallons for walls with two coats. The exact amount depends on the number of doors and windows, surface texture, and paint coverage rate. This calculator factors all of those variables into the estimate.
How many square feet does one gallon cover?
Most interior latex paints cover 350 to 400 square feet per gallon on smooth surfaces. Coverage drops to 250 to 300 square feet on rough or textured surfaces. Always check the coverage rate printed on the paint can for the most accurate figure.
Do I need to use primer?
Primer is recommended when painting new drywall, covering stains, painting over a dark color with a light one, or switching between oil-based and latex paint. It improves adhesion and reduces the number of topcoats needed.
Should I calculate walls and ceilings separately?
Yes, because ceiling paint is often a different product or finish than wall paint. Ceilings typically use flat paint while walls use eggshell or semi-gloss. Calculate each surface separately for accurate purchasing.
How do I measure irregular rooms?
Break irregular rooms into rectangular sections, measure each section separately, and add the areas together. For rooms with alcoves or bump-outs, treat each as a separate rectangle and sum the totals.