Exterior Paint Calculator

Calculate how many gallons of exterior paint you need for siding, trim, and primer. Includes surface type adjustments and cost estimates.

How to Use This Calculator

Painting your home's exterior is a significant project that requires careful planning. Accurate paint estimates prevent costly overages and frustrating mid-project supply runs.

  1. Enter your house dimensions or perimeter. For complex shapes, measure the perimeter by walking around the house.
  2. Specify the number of stories and wall height per story (typically 8-10 feet).
  3. Enter the number of doors and windows - these are subtracted from the paintable area.
  4. Indicate if you have gables (triangular sections at roof peaks) to add that area.
  5. Select your surface type - rougher surfaces need more paint per square foot.

Why This Matters

Exterior paint provides crucial protection against weather, UV damage, and moisture intrusion. Beyond aesthetics, a quality paint job prevents wood rot, protects against pests, and can significantly impact your home's value. Proper estimation ensures you buy enough paint from the same batch for color consistency.

  • Calculate siding and trim paint separately
  • Account for surface texture and coverage rates
  • Include primer quantities for proper preparation
  • Estimate costs for budget planning
  • Ensure color consistency with accurate quantities

Worked Examples

Single-Story Ranch

A 50' x 30' ranch home with 8-foot walls, 2 doors, 10 windows, and smooth siding.

Calculation: 160 ft perimeter x 8 ft = 1,280 sq ft - openings = ~1,100 sq ft x 2 coats
Result: 6 gallons siding paint, 2 gallons trim paint, 4 gallons primer.

Two-Story Colonial

A 40' x 35' colonial with 9-foot ceilings, 3 doors, 16 windows, and textured siding.

Calculation: 150 ft perimeter x 18 ft total height + gables - openings
Result: 14 gallons siding paint, 4 gallons trim paint, 8 gallons primer.

Victorian with Details

A 45' x 25' Victorian with complex trim, 2 stories, and multiple gables.

Calculation: Extensive trim and detail work doubles typical trim paint needs
Result: 8 gallons body paint, 6 gallons trim paint, 5 gallons primer.

Common Mistakes to Avoid

  • Underestimating by forgetting gables, dormers, and architectural details.
  • Using interior paint coverage rates - exterior surfaces often need more paint.
  • Skipping primer on bare wood or major color changes.
  • Not accounting for multiple coats - two coats is standard for durability.
  • Buying from different batches - color can vary between production runs.

Frequently Asked Questions

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