How to estimate exterior wall paint
For a simple rectangular building, exterior wall area can be approximated from perimeter multiplied by wall height. PrepMyBuild then subtracts planning allowances for doors and windows, applies coats, and converts the net area into paint volume.
Complex elevations need separate measurements
Gables, dormers, multiple stories, attached garages and irregular footprints are not captured perfectly by one rectangle. For those homes, break the exterior into simpler wall sections and calculate them separately.
Exterior surfaces can change coverage
Rough masonry, porous siding, spray application and dramatic color changes can affect real coverage. The coverage field is editable so you can use product-specific information.
Do not treat the result as a labor estimate
Access, preparation, scraping, repairs, masking and height can dominate professional painting cost. This calculator focuses on material planning.
The rectangular perimeter is 136 ft. PrepMyBuild converts that wall area, subtracts opening allowances, then applies two coats at the coverage rate you enter.