Paint Calculators | Free Construction Calculators
Calculate paint quantities, costs, and coverage
Paint Quantity Calculator
Calculate paint needed for your project
Paint Cost Calculator
Estimate painting project costs
Coverage Area Calculator
Calculate area covered by paint amount
Primer Calculator
Calculate primer needed for surfaces
About Paint Calculations
Accurate paint calculations are essential for project planning, budgeting, and ensuring you have the right amount of materials. Whether you're refreshing a single room, painting an entire house, or tackling exterior surfaces, knowing exactly how much paint you need prevents costly overages, avoids project delays from running short, and ensures consistent color coverage. Our professional paint calculators help homeowners, contractors, and painters determine precise quantities for interior and exterior projects, accounting for surface area, paint coverage rates, number of coats, and primer requirements.
Why Use Our Paint Calculators?
Accurate Quantity Estimates
Calculate exact paint and primer quantities needed to complete your project without excess waste or shortages mid-project.
Cost Planning & Budgeting
Estimate total material costs including paint, primer, and supplies to accurately budget your painting project.
Coverage Rate Calculations
Automatically account for standard coverage rates (350-400 sq ft per gallon) and adjust for surface type and paint quality.
Multiple Project Types
Support for interior rooms, exterior surfaces, primer requirements, and cost estimation across all painting scenarios.
Room-by-Room Planning
Calculate quantities for individual rooms or entire houses with consideration for windows, doors, and architectural features.
Professional Standards
Industry-standard calculations matching professional painter practices and paint manufacturer specifications.
Common Paint Calculations
Paint Quantity for Walls
Calculate total wall area and divide by coverage rate (typically 350-400 sq ft per gallon) to determine gallons needed, accounting for multiple coats.
Coverage Area Calculations
Determine the paintable area of walls, ceilings, and trim while properly accounting for windows, doors, and openings.
Primer Requirements
Determine when primer is necessary and calculate primer quantities, considering coverage rates and surface type.
Cost Estimation
Calculate total project costs based on paint prices, quantities needed, and additional supplies for accurate budgeting.
Interior vs Exterior Paint
Compare quantities and costs for interior and exterior projects, accounting for different coverage rates and product prices.
Multi-Coat Projects
Calculate additional paint needed for primer coat plus 1-3 topcoats, adjusting for project conditions and color coverage requirements.
Frequently Asked Questions
How much area does one gallon of paint cover?
Most interior paints cover 350-400 square feet per gallon with proper application. One coat on average wall surfaces typically requires one gallon per 350-400 sq ft. For ceilings with textured surfaces, coverage may be 250-300 sq ft per gallon. Exterior paints and primers may cover slightly less due to surface absorption and texture. Always check the manufacturer's specifications on the paint can, as coverage varies by paint quality, finish type, and application method.
How many coats of paint do I need?
Most interior painting projects require two coats for complete coverage and durability. Lighter colors may need 2-3 coats, especially when covering dark colors. Deep or saturated colors often only need one coat. Exterior paint typically requires 2 coats for long-lasting protection. Priming first can reduce the number of topcoats needed. High-quality paints may provide better coverage in fewer coats than budget brands.
When is primer required for a painting project?
Primer is essential in several situations: when covering stains or water damage, painting over dark colors with light paint, painting raw drywall or wood, painting glossy surfaces, and painting previously unpainted surfaces. For interior walls in good condition and same-color repainting, you may skip primer. Some premium paints have primer built in, but separate primer often provides better results. Primer blocks stains, improves adhesion, and ensures even topcoat coverage.
How do I calculate paint needed for rooms with windows and doors?
Measure wall area and subtract openings. For windows, calculate as about 10 sq ft per standard window. Doors are typically 20 sq ft each (both sides). Example: 10 ft wall × 8 ft height = 80 sq ft. Subtract 2 windows (20 sq ft) and 1 door (20 sq ft) = 40 sq ft to paint. Calculate all walls, then sum and divide by paint coverage (usually 350-400 sq ft per gallon). Conservative approach: calculate full wall area without subtracting small openings for extra coverage.
How can I estimate the total cost of my painting project?
Multiply gallons of paint needed by price per gallon, then add primer costs. Example: 350 sq ft ÷ 400 sq ft per gallon = 0.9 gallons. At $25/gallon = $22.50 paint cost. Add primer: 1 gallon × $12 = $12. Total material cost = $34.50. Professional labor typically costs $25-50 per hour or $1.50-3.00 per sq ft. Budget $300-500+ for labor on a typical room. Quality, brand, and finish type significantly impact paint costs.
What are the differences between interior and exterior paint?
Interior paints use softer resins, have lower VOC levels, and are easier to clean. Exterior paints contain stronger resins, UV blockers, and mildew inhibitors for weather resistance. Exterior paints withstand temperature extremes, moisture, and UV damage better than interior paints. Interior paint is not weather-resistant and will fail outdoors. Exterior paint can be used indoors but may have stronger odors and higher costs. Always use the correct type for its intended environment for best durability.
Paint Selection Guide
Interior Paint Finishes
- Flat/Matte: Hides imperfections well, best for low-traffic areas, ceilings, and bedrooms. Difficult to clean.
- Eggshell: Slight sheen, easy to clean, great for living rooms and bedrooms. Balances hiding power with durability.
- Satin: Soft sheen, very durable and washable, ideal for high-traffic areas, trim, and children's rooms.
- Semi-Gloss: Moisture-resistant and very durable, perfect for kitchens, bathrooms, doors, and trim.
- High-Gloss: Very durable and easy to clean, best for doors, cabinets, and accent features. Shows imperfections.
Interior vs Exterior Paint
Interior Paint Benefits
- Low VOC formulations available for better air quality
- Various sheens for different room requirements
- Easier application and cleanup with water
- Wide color selection and consistency
- More affordable than exterior paints
Exterior Paint Benefits
- UV and weather resistant for long-lasting protection
- Mildew and fade resistant formulations
- Withstands temperature extremes and moisture
- Premium durability for harsh outdoor conditions
- Self-priming options available for faster application
Painting Process & Best Practices
- Preparation: Clean, patch, and sand surfaces for smooth, even coverage and better paint adhesion.
- Protection: Cover floors with drop cloths, furniture, and tape edges with painter's tape for clean lines.
- Primer Application: Apply primer to new or problem surfaces, stains, or when coverage is critical (1-2 hours drying).
- First Topcoat: Apply paint in thin, even coats using smooth brush or roller strokes (2-4 hours drying).
- Drying Time: Allow proper drying between coats as specified on paint can (typically 2-4 hours for interior, 4-8 for exterior).
- Second Topcoat: Apply final coat for complete coverage, uniform color, and professional finish.
- Touch-ups: Address any missed spots, drips, or imperfections while paint is still fresh.
- Cleanup: Remove tape while paint is slightly tacky for clean edges, then clean brushes and equipment.
Essential Painting Tools & Supplies
- Brushes: Quality 2-3 inch angled brushes for cutting in edges and painting trim.
- Rollers: 9-inch roller frame with appropriate nap thickness ("⅜" for smooth, "½" for textured surfaces).
- Paint Tray: With liner for easy cleanup and efficient rolling.
- Painter's Tape: Quality tape for protecting trim, baseboards, and creating clean edge lines.
- Drop Cloths: Canvas or plastic sheets for protecting floors and furniture from drips and splatters.
- Sandpaper: Various grits (150-220) for surface preparation and smoothing between coats.
- Putty Knife: For patching holes, scraping loose paint, and smoothing joint compound.
- Caulk: Paintable caulk for gaps and cracks to prevent paint from settling into gaps.
Common Painting Mistakes to Avoid
- Skipping surface preparation, cleaning, and sanding for proper paint adhesion
- Not using primer when necessary or painting over glossy surfaces without preparation
- Applying paint too thick instead of multiple thin coats for better coverage and finish
- Painting in extreme temperatures (below 50°F or above 85°F) or high humidity
- Not allowing proper drying time between coats, causing poor adhesion and finish issues
- Using cheap, low-quality brushes and rollers that shed bristles or leave marks
- Removing painter's tape after paint fully dries instead of when slightly tacky for clean edges
- Not protecting adjacent surfaces, fixtures, and floors from drips and splatters
Professional Painting Guidance
Paint calculations should account for surface condition, paint quality, and environmental factors. Always verify exact measurements on-site, check paint coverage specifications on product labels, and consider climate conditions before painting. For large projects, consider hiring professional painters. Test paint samples in the actual lighting before committing to large quantities. Store leftover paint properly for future touch-ups and maintenance.