An exterior paint calculator estimates gallons needed for a house exterior by computing wall area from your perimeter and stories, then deducting windows and doors — giving separate amounts for body paint, trim paint, and primer.
House Dimensions
Paint Breakdown
At $50/gallon. Does not include brushes, rollers, tape, or labor.
Coverage by Surface Type
| Surface | Coverage/Gal | Body Paint (2 coats) |
|---|
How to Use the Exterior Paint Calculator
Painting a house exterior requires accurate material estimates to avoid multiple hardware store trips. This exterior paint calculator computes your net paintable wall area and converts it to gallons, accounting for windows, doors, surface texture, and the number of coats.
Step 1: Measure House Perimeter
Walk around your house and add up all four walls. For a rectangular home, this is 2 × (length + width). A typical ranch home might be 2 × (60 + 40) = 200 linear feet of perimeter. Then multiply by wall height per story and number of stories to get gross wall area.
Step 2: Count Windows and Doors
Count every window and exterior door. Average window size is about 15 sq ft (3 ft × 5 ft) and average door is 21 sq ft (3 ft × 7 ft). The calculator deducts these openings from your gross wall area to get the net paintable area — typically reducing total area by 10-15%.
Step 3: Choose Your Surface Type
Surface texture dramatically affects how much paint you need. Smooth vinyl or fiber cement siding covers 350-400 sq ft per gallon. Wood siding, T1-11, or moderately textured surfaces cover 250-300 sq ft per gallon. Stucco is the most absorptive at 200-250 sq ft per gallon and may require a second coat even for repainting.
Trim Paint Calculation
Trim paint covers door frames, window casings, fascia boards, corner boards, and other trim details. This calculator estimates trim area as approximately 1 foot of trim height × house perimeter plus window and door surround trim. Trim typically requires 1-3 gallons for an average home.
Adding a Waste Factor
Add 10% to your calculated gallons when purchasing to account for touch-ups, re-lid containers, and spillage. Most paint stores will accept unopened returns, so it's better to buy slightly more than to run short mid-project.
FAQ
Is this exterior paint calculator free?
Yes, completely free with no signup required. All calculations run in your browser — nothing is sent to any server.
Is my data private?
Absolutely. All calculations happen locally in your browser. Your house dimensions and project details are never transmitted or stored remotely.
How many gallons of paint do I need for the exterior of a house?
A typical 2,000 sq ft two-story home requires 8-12 gallons of paint for two coats, after deducting windows and doors. Coverage varies by surface texture — smooth siding covers 350-400 sq ft per gallon, textured siding 250-300 sq ft per gallon, and stucco only 200-250 sq ft per gallon.
Do I need primer for exterior painting?
Primer is strongly recommended when painting over bare wood, raw cement board, heavily weathered surfaces, or when making a dramatic color change. New siding always needs primer. Primer improves adhesion, seals porous surfaces, and helps the finish coat cover evenly — typically saving paint overall.
How much does it cost to paint a house exterior?
Professional exterior house painting typically costs $2,500-8,000 for an average two-story home. Labor (surface prep, painting, cleanup) represents 70-80% of the cost. DIY material cost for a 2,000 sq ft home runs $200-600 for paint plus $50-150 for primer and supplies.
How much paint do I need for trim?
Trim paint — doors, window frames, fascia, and corner boards — typically requires 1-2 quarts per 100 linear feet of trim run. A typical 2-story home uses 1-3 gallons of trim paint. This calculator estimates trim based on your perimeter and number of windows and doors.
What is the best number of coats for exterior paint?
Two finish coats are the standard for new work or a full repaint. If you're repainting the same color on a surface in good condition, one well-applied coat may suffice. Primer counts as one coat but does not replace finish coats — always apply at least one finish coat over primer.