Free room paint calculator & cost estimator
Paint Calculator: Estimate Gallons & Cost
The free paint cost calculator and room paint estimator for any space. Enter room dimensions, subtract doors and windows, pick coats and finish, and get gallons and total cost in under a minute. Then preview the color on your walls with our AI paint visualizer before you buy.
Your first design is free with Google sign-in.
What this tool solves
- • Calculates exact paint gallons needed.
- • Subtracts doors and windows automatically.
- • Includes primer and ceiling options.
- • Estimates total material cost.
Enter room dimensions
Measure wall-to-wall interior dimensions.
Estimates only. Coverage varies by paint quality and surface.
Step 1: Room size
Step 2: Doors & windows
Step 3: Paint options
Paint estimate
Based on 2 coats at 350 sq ft per gallon (Eggshell / Satin), plus a 10% buffer.
3 gallons of paint
Calculated: 2.6 gallons (rounded up)
Selected finish: Eggshell / Satin
Estimated cost
Does not include brushes, rollers, tape, or drop cloths.
Visualize paint colors first?
Upload a room photo and see different wall colors with AI before you buy.
See these colors on your wallsPaint calculator FAQs
How much paint do I need for a 12x12 room?
A 12x12 room with 9ft ceilings has about 432 sq ft of wall space. After subtracting a door and two windows, you need roughly 1.5-2 gallons for two coats. Use the calculator above for exact amounts.
How many square feet does a gallon of paint cover?
One gallon of paint typically covers 350-400 square feet per coat. Coverage varies by paint quality, surface texture, and application method. This calculator uses 350 sq ft as a conservative estimate.
1 coat vs 2 coats: which do I need?
Two coats is the standard for full, even coverage, especially when switching colors or painting over a dark shade. One coat works for light touch-ups in the same color. The calculator adjusts your total automatically based on the number of coats you select.
Should I subtract windows and doors from paint calculations?
Yes. A standard interior door is about 21 sq ft (3x7ft) and a typical window is also around 21 sq ft. Skipping this step leads to over-buying by half a gallon or more in larger rooms. Enter door and window counts above and the calculator handles the deduction automatically.
Which paint finish covers more square feet per gallon?
Matte and flat finishes spread furthest at about 375 sq ft per gallon and hide imperfections on bedroom walls. Eggshell and satin (~350 sq ft per gallon) clean more easily and suit hallways and kids rooms. Semi-gloss (~325 sq ft per gallon) is best for trim, doors, and bathrooms where moisture resistance matters.
Do I need primer before painting?
Primer is recommended when painting over dark colors, new drywall, patched areas, or stained surfaces. Many modern paints include primer, but separate primer provides better coverage and adhesion.
Should I buy extra paint?
Yes, buy 10-15% more than calculated for touch-ups, mistakes, and future repairs. This calculator rounds up to whole gallons which typically provides this buffer.
How much does it cost to paint a room?
Paint material for an average bedroom runs about $45 to $90 (one to two gallons). If you hire a pro, labor typically adds $1.50 to $4 per square foot of wall, or roughly $300 to $800 per room, depending on prep, ceiling height, and your area. This calculator estimates paint and primer cost; add labor on top if you are not painting it yourself.
How do I calculate paint in liters instead of gallons?
Switch the units to meters to see area in square meters. The estimate is shown in gallons; to convert, one US gallon is about 3.79 liters, so a 1 gallon result is roughly 3.8 liters and a 2.5 liter tin covers about two thirds of a gallon. In metric markets the coverage rate is usually printed per liter on the can.
How much paint do I need for trim, doors, and baseboards?
Tick "Paint door frames and trim" to add about 30 square feet per door for casing and baseboards. As a rule of thumb, one quart of trim paint covers the trim in an average room. Trim usually takes semi-gloss for durability, which the finish selector factors into coverage.
Can I preview paint colors on my room with AI?
Yes. Once this calculator gives you gallons and cost, open the Change Wall tool to repaint your room photo in any of our preset colors (off-white, sage, navy, terracotta, charcoal, blush) or describe a custom shade. The AI applies the new color to the walls while keeping furniture and layout untouched.
Explore more tools
Plan your full room project with spacing, budgets, and palettes.
How much paint do I need?
One gallon of paint covers roughly 350–400 sq ft of wall area with a single coat. For most rooms, plan on 1–2 gallons for walls depending on room size, number of coats, and paint finish.
How many gallons for a 12×12 bedroom?
A 12×12 room with 9ft ceilings has roughly 288 sq ft of total wall area. After subtracting one door (~21 sq ft) and two windows (~42 sq ft), you're left with about 225 sq ft of paintable surface. With 2 coats and a 10% waste buffer, that's around 1.4 gallons, so two 1-gallon cans is the practical purchase.
1 coat vs 2 coats: does it matter?
Two coats is the standard for full, even coverage, especially when switching colors or painting over a dark shade. One coat can work for light touch-ups using the same color. The calculator adjusts your total automatically based on which you choose.
Should I subtract windows and doors?
Yes. A standard interior door is about 21 sq ft (3×7ft) and a typical window is also around 21 sq ft. Skipping this step leads to over-buying by half a gallon or more in larger rooms. Enter your door and window counts above and the calculator handles the deduction automatically.
Does ceiling paint count separately?
Yes, ceilings are a separate surface with a different coverage rate (flat/matte finishes spread further on smooth ceilings). Enable "Include ceiling" in the calculator to add a ceiling estimate on top of your wall total. Most bedrooms add about 0.5–1 gallon for the ceiling.
Which paint finish should I choose?
Finish affects both coverage and durability. Matte and flat finishes hide imperfections and cover about 375 sq ft per gallon, making them good for low-traffic bedroom walls. Eggshell and satin (~350 sq ft/gallon) are easier to clean, making them a better choice for hallways and kids' rooms. Semi-gloss (~325 sq ft/gallon) is best for trim, doors, and bathrooms where moisture resistance matters.
How much does it cost to paint a room?
For a typical room, paint alone is about $45 to $90 (one to two gallons at $45 a gallon), which is the figure this paint cost calculator returns. If you hire a painter, labor usually adds $1.50 to $4 per square foot of wall, or roughly $300 to $800 per room, depending on prep work, ceiling height, the number of coats, and your local rates. Doing it yourself keeps the cost to materials plus brushes, rollers, tape, and drop cloths.
How do I calculate paint in liters?
Switch the units toggle to meters to work in square meters. The result is shown in gallons, which convert cleanly to liters: one US gallon is about 3.79 liters, so a 1 gallon estimate is roughly 3.8 liters and a 2.5 liter tin covers about two thirds of a gallon. In metric markets the coverage rate on the can is listed per liter, so you can enter it under the advanced coverage option for an exact match.
Continue with ideas and playbooks
Once your paint quantities are set, explore room ideas and step-by-step playbooks to execute the full design.