Paint Calculator
Determine the exact amount of paint needed for walls, ceilings, and rooms based on dimensions and openings
Room Dimensions
Openings to Exclude
Paint Options
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Calculate Exactly How Much Paint You Need
Planning a painting project? Our paint calculator helps you determine the precise amount of paint needed for any room or surface. Avoid buying too much or running short mid-project by calculating based on your room dimensions, number of doors and windows, and desired number of coats. Get accurate estimates in gallons or liters with cost projections.
How Paint Coverage Works
Paint coverage varies by type and surface, but most interior latex paints cover approximately 350-400 square feet per gallon on smooth surfaces. Textured walls, porous surfaces, or dramatic color changes may require more paint. We calculate the paintable area by measuring walls (and optionally ceilings), then subtracting doors and windows to give you an accurate estimate.
Paint Calculation Formula
Paint Needed = (Wall Area + Ceiling Area - Doors/Windows) × Coats ÷ Coverage RateHow to Calculate Paint Needed
Measure your room's length, width, and height
Count the number of standard doors and windows
Select the number of coats (2 is recommended for most projects)
Choose whether to include the ceiling
View your results including recommended gallons and cost estimates
Common Use Cases
DIY Home Projects
Plan your painting project with accurate paint quantities before heading to the store.
Contractor Estimates
Create accurate material quotes for painting jobs and avoid under or over-ordering.
Budget Planning
Estimate total paint costs across different quality levels before starting your project.
Multi-Room Projects
Calculate paint needs for multiple rooms to buy in bulk and save money.
Why Use Our Paint Calculator?
One Store Trip
Avoid multiple trips to the store by buying the right amount the first time
No Wasted Paint
Save money by not over-purchasing paint that goes to waste
Door & Window Accuracy
Get accurate estimates that account for doors, windows, and multiple coats
Price Tier Comparison
Compare costs across budget, mid-range, and premium paint options
Imperial & Metric
Works in both imperial (feet/gallons) and metric (meters/liters) units
Frequently Asked Questions
Most projects require 2 coats for even coverage and durability. Use 1 coat only for touch-ups or repainting the same color. Consider 3 coats when covering dark colors with light, using deep/bold colors, or painting over bare drywall.
Surface texture is the biggest factor—smooth walls cover more than textured. Color changes matter too: covering dark with light or vice versa needs more paint. New drywall absorbs more paint than previously painted surfaces. Primer helps with difficult surfaces.
Our calculator includes a 10% buffer in the recommended amount. This accounts for waste, spills, and touch-ups. Keep leftover paint for future touch-ups—store in a cool, dry place with the lid tightly sealed.
Break the room into rectangular sections and add them together. For vaulted ceilings, calculate as if flat then add 20%. For accent walls, measure just that wall's dimensions and calculate separately.
Budget paint (~$25-35/gal) works for rentals or low-traffic areas. Mid-range (~$40-55/gal) offers good coverage and durability for most homes. Premium (~$60-80/gal) provides excellent coverage, durability, and often includes primers.