How to Use
- 1.
Enter the first room's length, width, height, wall count, and measurement unit.
- 2.
Add doors and windows, enable the ceiling if needed, and choose interior or exterior paint, finish, and surface texture.
- 3.
Set coats, container coverage, waste percentage, primer settings, and any accent walls.
- 4.
Add more labeled rooms or exterior sections and review individual plus project totals.
- 5.
Enter paint and optional supply prices to calculate the estimated shopping cost.
- 6.
Copy, save, share, or print the shopping list, then verify product coverage and measurements before buying.
Features
Length, width, and height inputs
Feet and meter units
Four-wall or custom wall count
Wall and optional ceiling area
Multiple labeled rooms
Interior and exterior paint
Editable coverage per gallon
One, two, or custom coats
Standard or custom doors and windows
Opening area deduction
Smooth, textured, and rough surface adjustment
Matte, eggshell, satin, semi-gloss, and gloss finishes
Accent wall area and color preview
Separate main and accent paint quantities
Primer coats and coverage
Waste and touch-up buffer
Exact gallons and liters
Whole-gallon plus quart smart rounding
Price per gallon or liter
Optional brush, roller, tape, and supply costs
Room breakdown chart
Local project history
Copyable shopping list
Browser share
Print or save as PDF
Responsive dark-mode interface
Frequently Asked Questions
How do I calculate paint needed for a room?+
Calculate wall area, subtract doors and windows, add ceiling area if painted, multiply by coats and waste, then divide by the paint's effective coverage rate.
How much area does one gallon of paint cover?+
Many products list roughly 350 to 400 square feet per gallon on suitable smooth surfaces, but always use the specific container's coverage and account for surface condition.
Does the calculator subtract doors and windows?+
Yes. Enter counts and dimensions for each room. Their area is subtracted from gross wall area without making paintable area negative.
Can I calculate paint for multiple rooms?+
Yes. Add labeled rooms or sections with independent dimensions, coats, openings, surfaces, colors, and coverage rates.
How is ceiling paint calculated?+
A flat rectangular ceiling uses length times width. Irregular or sloped ceilings should be measured as separate sections.
Why does a textured wall need more paint?+
Texture and porosity increase surface area and can reduce practical coverage. The calculator lowers effective coverage for textured and rough selections.
How many coats should I use?+
It depends on the product, substrate, preparation, previous color, and new color. Two coats are a common planning choice, but manufacturer instructions should decide.
How does the accent wall estimate work?+
It uses the average wall area in that room multiplied by the selected accent-wall count. Add an unequal accent wall as a separate section for better precision.
Do I need primer?+
Primer can help on bare, porous, stained, repaired, glossy, or strongly contrasting surfaces. Confirm compatibility and preparation with the coating manufacturer.
What is smart can rounding?+
It separates exact paint quantity into whole one-gallon cans and quarter-gallon quarts. Check actual package sizes and whether the chosen tint is sold in smaller containers.
Does the cost include labor?+
No. It includes entered paint and optional supply costs only. Labor, tax, repairs, delivery, and equipment are not automatically included.
Can I save or print the result?+
Yes. Save locally, copy a shopping list, share the tool, or print and save the project as a PDF.
About this tool
Free Paint Calculator
Use this free Paint Calculator to estimate paint and primer for one room or a complete multi-room project. Enter room dimensions, wall count, openings, coats, coverage, and waste to receive results in gallons and liters plus a practical shopping estimate.
How the Paint Calculator Works
The calculator finds gross wall area from room dimensions and wall height, subtracts entered doors and windows, adds an optional ceiling, then applies coats and a waste allowance. Paint quantity equals adjusted paintable area divided by the effective coverage rate. Textured and rough surfaces reduce effective coverage because they commonly require more material.
Calculate Wall Area for Paint
For a standard four-wall rectangular room, wall area equals perimeter multiplied by height. A 12-by-10-foot room with 8-foot walls has a 44-foot perimeter and 352 square feet of gross wall area before openings. Custom wall count scales the average wall area for hallways and irregular spaces.
Doors and Windows Deductions
Add standard or custom door and window dimensions. Their combined area is subtracted from gross wall area without allowing the result to fall below zero. Small trim and molding surfaces are not added unless they are included in your entered paintable area or handled separately.
Ceiling Paint Calculator
Enable ceiling painting for any room. Ceiling area is length multiplied by width and uses the room's selected coats, surface adjustment, coverage rate, and waste allowance. Sloped, vaulted, coffered, or irregular ceilings should be measured as separate sections for better accuracy.
Multiple Room Paint Project
Add bedrooms, living rooms, kitchens, hallways, exterior sections, or other labeled areas. Each room can use different dimensions, units, paint type, finish, surface texture, coats, openings, accent walls, and colors. Project totals combine all included paint quantities.
Interior and Exterior Paint Coverage
Coverage printed on the paint container should be the primary input. Typical planning values often fall near 350 to 400 square feet per gallon on smooth prepared surfaces, but product, substrate, application, porosity, color change, and weather can alter coverage. Exterior and rough surfaces often require more paint.
Paint Coats and Waste Allowance
One coat may be enough for a similar color on a well-prepared surface, while major color changes or new surfaces often need two or more coats. Waste allowance helps cover roller loading, spills, touch-ups, and leftover paint for future repairs. The correct allowance depends on the project.
Accent Wall Paint Calculator
Choose one or more accent walls and a visual color. The calculator estimates accent-wall area and separates its approximate paint quantity from the main-color quantity. For unequal wall widths, model the accent wall as its own room section for a more precise estimate.
Primer Needed Calculator
Enable primer, enter primer coats and coverage, and receive a separate quantity. Primer may be useful on bare drywall, porous materials, stains, repairs, glossy surfaces, or major color changes. Follow the coating manufacturer's preparation and compatibility guidance.
Gallons, Liters, and Smart Can Rounding
Results display exact gallons and liters. Smart rounding converts the exact amount into whole one-gallon cans plus quarts, avoiding a simple round-up that can overstate a small remainder. Actual package sizes differ by country and product.
Paint Cost and Supplies Estimate
Enter a price per gallon or liter and optional costs for rollers, brushes, tape, and other supplies. The estimate does not automatically include labor, tax, delivery, surface repair, scaffolding, caulk, drop cloths, or specialized equipment.
Save, Copy, Print, and Export a Shopping List
Save projects in local browser storage, copy a room-by-room shopping list, share the tool, or print the page and choose Save as PDF. Saved projects remain on the current device unless copied or exported.
Verify Coverage Before Buying Paint
This calculator is a planning estimate. Recheck measurements, number of coats, opening deductions, substrate condition, product coverage, tint availability, package sizes, and store return policy before purchasing. When color consistency matters, buy enough paint from the same batch and mix containers together as recommended.
Measure floors, ceilings, and irregular sections first with the Square Footage Calculator, sample a color from an inspiration image using the Image Color Picker, or check a percentage-based waste allowance with the Percentage Calculator.