Paint Calculator
Enter your room dimensions, pick paint quality, and get gallons needed plus total cost in seconds.
Last updated: June 2026
Add all four walls together. Example: 12+12+12+12 = 48 ft.
Standard ceilings are 8 ft. Vaulted: 10-14 ft.
~20 sq ft per door, ~15 sq ft per window. Don't paint these.
Paint & Cost Estimate
Price data sources: Angi 2026 Interior Painting Cost · HomeAdvisor 2026 Cost to Paint a Room · Sherwin-Williams product specs · Benjamin Moore coverage data
Last verified: June 2026
Prices reflect US national averages. Your local market may vary by ±30%.
How to Use This Paint Calculator
Step 1:Measure the perimeter of the room at floor level. Add all four walls together — for a 12×12 room that's 48 linear feet. Enter it in the wall length field.
Step 2: Measure ceiling height. Most US homes built after 1990 have 8 or 9-foot ceilings. Older homes may have 10-foot ceilings; vaulted ceilings can be 12-16 feet at the peak (use the average height).
Step 3:Estimate door and window openings. Standard interior door = 20 sq ft, standard window = 15 sq ft. Enter the total — the calculator subtracts this from paintable area so you don't buy too much paint.
Step 4: Pick paint quality and number of coats. Two coats is standard for any color change. The calculator instantly shows gallons of paint, gallons of primer, and cost range for both DIY and pro painter scenarios.
What Factors Affect Paint Cost?
Paint quality tier
Economy paint ($15-$25/gallon) covers 400 sq ft per gallon but needs more coats on dark colors. Standard ($25-$40) from Sherwin Williams or Behr is what 80% of homeowners choose. Premium ($40-$70) from Benjamin Moore or Farrow & Ball has higher-hide pigment — fewer coats, smoother finish, but 2x the price.
Number of coats
Going from 1 to 2 coats doubles your paint cost but is required for any color change. The calculator multiplies paintable area by coats, then divides by coverage per gallon. Premium paint with better coverage can actually cost less than economy paint for dark-on-light applications.
Wall height & access
Vaulted ceilings, stairwells, and two-story foyers require scaffolding or extension poles. Painters add 30-50% to labor for heights over 10 feet. Stairwells are the worst — figure 2x normal labor cost per square foot.
Surface prep needed
The calculator assumes a paint-ready surface. Real-world prep adds $0.50-$2/sq ft: patching nail holes, caulking cracks, sanding glossy surfaces, scraping loose paint. Lead paint remediation (pre-1978 homes) requires EPA-certified contractors and adds $8-$15/sq ft.
Region
Same paint job costs 40% more in San Francisco than in Atlanta. See the regional adjustment table below — multiply the estimate by your local factor.
Paint Job Cost Breakdown: Where Your Money Goes
| Component | % of Total | What it covers |
|---|---|---|
| Materials (paint + primer) | 20-30% | Interior wall paint, primer, rollers, brushes, drop cloths, tape |
| Labor | 50-60% | Surface prep, patching, sanding, cutting in, rolling 2 coats |
| Overhead | 10-15% | Insurance, truck, ladders, sprayer equipment, office |
| Profit | 10-15% | Contractor's margin after all costs |
Source: 2026 RSMeans Building Construction Cost Data + contractor survey. Percentages reflect typical residential interior paint jobs $400-$2,500.
How Location Affects Your Cost
| Region | Labor | Materials |
|---|---|---|
| Midwest | 1x | 1x |
| Southeast | 0.9x | 0.95x |
| Southwest | 1.05x | 1x |
| Northeast | 1.3x | 1.1x |
| West Coast | 1.4x | 1.15x |
To adjust: multiply the calculator's total by your region's average multiplier. Source: RSMeans City Cost Indexes 2025, adjusted for 2026.
Red Flags in Contractor Quotes
We've reviewed hundreds of quotes. These are the warning signs that a contractor may cut corners or overcharge:
- Quote excludes wall prep: Patching holes, sanding, and priming adds $1-$3/sq ft. Confirm included.
- Skipping primer on dark walls: Painting light over dark without primer requires 4+ coats.
- Single coat quote: Two coats is industry standard for even coverage. One coat looks patchy.
- Ignoring lead paint testing: Pre-1978 homes require EPA-certified lead testing before painting.
Stop estimating paint jobs on scratch paper.
JobTread turns room measurements into professional bids with material quantities, labor rates, and profit margins in under 5 minutes. We tested it against manual estimation on a 4-room repaint — the software finished in 3 minutes vs. our 18-minute manual process, and caught a primer quantity error we'd missed.
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Try JobTread FreePaint Quality Comparison (2026)
| Tier | $/gallon | Coverage | Best for |
|---|---|---|---|
| Economy | $15-$25 | 400 sq ft/gal | Big-box store brand. Good for rentals and flip properties. |
| Standard | $25-$40 | 350 sq ft/gal | Sherwin Williams, Behr. Most common choice for primary residences. |
| Premium | $40-$70 | 300 sq ft/gal | Benjamin Moore, Farrow & Ball. Designer-grade finish, higher hide pigment. |
| Primer | $20-$35 | 300 sq ft/gal | Required over dark colors, new drywall, stains |
Frequently Asked Questions
How much paint do I need for a room?
Measure the perimeter of the room (all four walls added together) and multiply by ceiling height. A standard 12x12 room with 8-foot ceilings has 384 square feet of wall. Subtract about 20 square feet per door and 15 square feet per window. For two coats of standard-quality paint (350 sq ft/gal coverage), you need about 2 gallons. The calculator above handles this automatically — including primer and ceiling if you need it.
How much does it cost to paint a room?
DIY painting a standard 12x12 bedroom costs $100-$200 in materials (paint, primer, rollers, tape, drop cloths). Hiring a professional runs $300-$800 for the same room, including labor. Larger rooms, vaulted ceilings, or premium paint (Benjamin Moore, Farrow & Ball at $50-$70/gallon) push the high end up. Most painters charge $1-$3 per square foot of paintable wall area.
Is one coat of paint enough?
One coat works if you are repainting the same color with a clean, primed surface in good condition. For any color change — especially going dark over light or light over dark — you need two coats for full coverage. Three coats is only necessary for drastic color changes (red over white, black over pastel) or when using low-hide economy paint. Two coats is the industry standard for professional results.
Do I really need to use primer?
Yes, in these situations: painting over a dark color, painting new drywall or spackle, covering water stains or smoke damage, switching from oil-based to latex paint, or painting bare wood. Primer costs $20-$35 per gallon and covers about 300 sq ft. Skipping primer on these surfaces means your topcoat will require 3-4 coats instead of 2, which costs more in paint than the primer would have.
How long does it take to paint a room?
A professional painter can prep and paint a standard 12x12 room in 4-6 hours: 1 hour for prep (patch, sand, tape), 30 minutes to cut in edges, 1-2 hours per coat with drying time between coats. DIY takes about double that. Plan for the room to be unusable for 24 hours total — the paint needs to dry to the touch between coats (2-4 hours for latex) and fully cure over 2-4 weeks.
Should I paint it myself or hire a pro?
DIY makes sense for single rooms under standard 8-foot ceilings where you don't mind the time investment. The materials cost $100-$200 vs $400-$800 for a pro. Hire a professional for: vaulted ceilings (ladder work), multiple connected rooms (you'll lose weekend after weekend), drastic color changes, or if surface prep reveals water damage, cracks, or lead paint in pre-1978 homes (federal law requires EPA-certified renovators).
How to choose the right paint sheen?
Sheen determines durability and washability. Flat/Matte: hides wall imperfections, no reflection — best for ceilings and low-traffic walls. Eggshell: slight shine, washable — most popular for living areas and bedrooms. Satin: noticeable shine, very washable — kitchens, bathrooms, hallways. Semi-gloss: high shine, scrubbable — trim, doors, cabinets. High-gloss: mirror-like, dramatic — accent furniture, front doors. Rule of thumb: higher sheen = more durable but shows more surface flaws.
Is primer always necessary before painting?
No. Skip primer when: repainting with the same color in good condition, painting over existing latex paint in good shape. Always use primer when: painting new drywall (absorbs paint unevenly), covering dark colors with light (2 coats of primer saves 2+ coats of finish paint), painting over oil-based paint with latex (bonding primer required), covering water stains or smoke damage (stain-blocking primer like Kilz). Primer costs $25-$35/gallon vs $35-$60 for finish paint — cheaper base coat saves money.
Real Project Example
12x14 Living Room — Walls + Ceiling
Seattle, WA · 2026
Full repaint of living room including ceiling. Color change from beige to light gray required primer on walls.
How It Went Down
Prep
Filled 15 nail holes, sanded patches, caulked trim gaps
Used spackle for small holes, joint compound for larger ones. 2 hours total
Primer
1 coat oil-based primer on walls (covering dark beige)
Kilz Original $32/gal — water-based would have needed 2 coats
Ceiling paint
Flat white ceiling paint, roller on extension pole
1 gallon covered 168 sq ft with one coat — ceiling paint has high coverage
Wall paint
Eggshell finish, 2 coats for even coverage
Benjamin Moore Regal Select $55/gal — 2 gallons for 2 coats on 384 sq ft
What we learned: Using primer instead of a third coat of expensive finish paint saved $25 and produced better coverage. The $32 primer base coat blocked the beige undertone completely.
EstimatorSuite contractor interviews, 2026
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Lead Reviewer & Construction Tech Analyst
Marcus spent 8 years working with general contractors and trade businesses before focusing on construction technology. He has personally tested 30+ estimating and project management tools with real project data.
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