Exterior Paint Calculator
Gallons of paint for a house exterior.
Enter your values
Enter the house perimeter in ft.
Enter the wall height in ft.
Enter the doors/windows area in sq ft.
Enter the coverage per gallon in sq ft.
Enter the number of coats you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Paint needed
- 13.8 gal
- Net wall area
- 2410 sq ft
- 5-gallon buckets
- 2.75
- Primer (1 coat)
- 6.9 gal
Quick answer
Exterior paint need is wall area divided by coverage per gallon, multiplied by the number of coats.
gallons = (wall area x coats) / coverage per gallon
At a glance
| What it does | Gallons of paint for a house exterior. |
|---|---|
| Category | Home & DIY |
| Inputs needed | House perimeter, Wall height, Doors/windows area, Coverage per gallon, Number of coats |
| Main output | Paint needed |
| Formula | gallons = (wall area x coats) / coverage per gallon |
| Cost | Free — no sign-up, no download |
How to use the Exterior Paint Calculator
- 1Measure the house perimeter and average wall height.
- 2Subtract the area of doors and windows.
- 3Choose coverage per gallon (usually 300-400 sq ft) and number of coats.
Inputs explained
- House perimeter(ft)
- Enter the house perimeter in ft.
- Wall height(ft)
- Enter the wall height in ft.
- Doors/windows area(sq ft)
- Enter the doors/windows area in sq ft.
- Coverage per gallon(sq ft)
- Enter the coverage per gallon in sq ft.
- Number of coats
- Enter the number of coats you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- House perimeter160 ft
- Wall height16 ft
- Doors/windows area150 sq ft
- Coverage per gallon350 sq ft
- Number of coats2
Results
- Paint needed13.8 gal
- Net wall area2410 sq ft
- 5-gallon buckets2.75
- Primer (1 coat)6.9 gal
Frequently asked questions
Do I need primer on old paint?
Usually not for a spot-clean repaint, but bare wood, stucco or a big colour change needs primer.
Does texture change coverage?
Yes — rough stucco or wood siding can cut coverage by 20-30% versus smooth siding.
What do I need to enter into the Exterior Paint Calculator?
Just 5 values: house perimeter, wall height, doors/windows area, coverage per gallon, number of coats. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Exterior Paint Calculator work out the answer?
Exterior paint need is wall area divided by coverage per gallon, multiplied by the number of coats. It applies the formula gallons = (wall area x coats) / coverage per gallon and shows the working so you can check each step by hand.
Is the Exterior Paint Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.