Exterior Paint Calculator
Estimate the amount of paint you need for your house exterior. Enter your house dimensions, account for windows and doors, and get accurate paint estimates in gallons and liters. Includes primer, topcoat, and total cost estimation.
What Is an Exterior Paint Calculator?
An exterior paint calculator helps you estimate the amount of paint needed to cover the outside of a house or building. It calculates the total paintable wall area based on the building's dimensions, subtracts areas for doors and windows, and accounts for multiple coats, primer, and waste factor.
This calculator supports three house shapes — Rectangle, Square, and L-Shape — and includes features for gable ends, trim, and custom coverage rates.
How Does the Exterior Paint Calculator Work?
The calculator follows these steps:
Step 1: Calculate the perimeter of the house based on the selected shape.
Step 2: Multiply perimeter by wall height to get gross wall area.
Step 3: Add gable area (if specified).
Step 4: Subtract door and window areas.
Step 5: Apply waste factor and multiply by the number of coats.
Step 6: Divide by coverage per gallon to get gallons needed.
Standard deductions: 21 sq ft per door and 15 sq ft per window.
Why Use This Exterior Paint Calculator?
- Three Shapes: Supports rectangle, square, and L-shaped houses.
- Gable & Trim: Account for gable ends and trim areas.
- Multiple Coats: Calculate paint for 1-3 coats.
- Primer Option: Estimate primer needed separately.
- Cost Estimation: Enter price per gallon to estimate total cost.
- Free & Private: No registration, no data storage.
❓ Exterior Paint Calculator FAQ
How do I calculate exterior paint for my house?
Measure the length, width, and height of your house. Enter these dimensions into the calculator, along with the number of doors and windows. The calculator will estimate the total paintable area and paint needed.
What is the formula for calculating exterior paint?
Formula: (Perimeter × Wall Height + Gable Area − Door Area − Window Area) × Coats × Waste Factor ÷ Coverage per Gallon.
How much area does a gallon of exterior paint cover?
Typically 350-450 sq ft per gallon, depending on surface texture and paint quality. This calculator includes coverage options from 350 to 500 sq ft per gallon.
How many gallons of exterior paint do I need for a 2,000 sq ft house?
For a 2,000 sq ft house with 2 coats, you'll typically need 10-12 gallons of paint. Use this calculator for an accurate estimate based on your specific dimensions.
Do I need primer for exterior painting?
Primer is recommended for bare wood, major color changes, or when painting over stains. It improves adhesion and coverage. The calculator includes an optional primer estimation.
How do I calculate the perimeter of my house?
Add the length of all exterior walls. For a rectangle: 2 × (Length + Width). For an L-shape: add all the exterior wall segments.
How much do doors and windows reduce paint area?
Each door reduces the paintable area by about 21 sq ft, and each window by about 15 sq ft. The calculator subtracts these automatically.
What is a gable and how does it affect paint calculation?
A gable is the triangular portion of a wall under a peaked roof. It adds to the paintable area. Enter the gable height (from the top of the wall to the peak) to include it in the calculation.
How do I estimate the cost of exterior painting?
Enter the price per gallon of paint. The calculator will multiply the total gallons needed by the price to estimate the total paint cost.
What is a waste factor in painting?
The waste factor accounts for paint lost to cutting in, touch-ups, spills, and over-spray. A typical waste factor is 10-15%.
How many coats of exterior paint do I need?
Most exterior paint jobs need 2 coats for full coverage and durability. 1 coat is sufficient for touch-ups, while 3 coats may be needed for major color changes.
What is the best time of year to paint a house exterior?
The best time is when temperatures are between 50°F and 85°F (10°C-30°C) with low humidity. Avoid painting in direct sunlight or when rain is expected.
How long does exterior paint take to dry?
Exterior paint is typically dry to the touch in 1-2 hours and can be recoated in 4-6 hours. Full curing takes 7-30 days depending on weather conditions.
What type of paint is best for exterior walls?
Acrylic latex paint is the most common choice for exterior walls. It's durable, flexible, and resistant to fading and mildew. For wood, use a high-quality exterior primer.
How do I prepare exterior walls for painting?
Clean the walls to remove dirt and mildew, repair any cracks or damage, sand rough areas, and apply primer if needed. Proper preparation is key to a long-lasting paint job.
How long does exterior paint last?
Quality exterior paint can last 5-10 years, depending on climate, surface type, and preparation. Regular maintenance can extend the life of your paint job.
Can I use this calculator for commercial buildings?
Yes, this calculator works for any rectangular or L-shaped building. For complex commercial buildings, break the structure into sections and calculate each separately.