Paint Area Calculator

Calculate paint square footage for walls, ceilings, rooms, trim, doors, and remodeling projects. Estimate paint gallons, primer gallons, coats, waste, and project cost.

Calculate Paint Area

Paint Area = Wall Area + Ceiling Area − Door Area − Window Area.
Your result will appear here.

How the paint area calculator works

Room walls mode:
The calculator uses room perimeter times wall height, then subtracts doors and windows.

Walls and ceiling mode:
The calculator adds wall area and ceiling area before subtracting openings.

Single wall mode:
The calculator multiplies wall length by wall height and the number of same-size walls.

Known area mode:
The calculator starts with your known paint area and estimates coats, paint gallons, primer gallons, waste, and cost.

Why use a paint area calculator?

A paint area calculator helps estimate square footage for interior walls, ceilings, trim, exterior walls, remodels, bedrooms, basements, garages, and painting projects.

It can help calculate gross paint area, opening deductions, net paint area, trim area, paint gallons, primer gallons, waste, supplies, labor, and estimated cost.

What your result means

Your result shows gross paint area, door and window opening area, net paint area, trim paint area, area with waste, paint gallons, primer gallons, and estimated project cost.

Paint area formulas

Frequently asked questions

How do I calculate paint square footage?

For room walls, add the room length and width, multiply by 2 to get the perimeter, then multiply by wall height. Subtract doors and windows if needed.

How much area does one gallon of paint cover?

Many paints cover about 300 to 400 square feet per gallon, but coverage depends on the product, surface texture, color change, and application method.

Should I subtract doors and windows from paint area?

Yes, subtracting openings gives a more accurate estimate. For small rooms, some people leave small openings in the estimate to allow for waste and touchups.

How many coats of paint should I estimate?

Two coats is common for many wall painting projects. Strong color changes, porous surfaces, repairs, and new drywall may require primer or additional coats.

Is this paint calculator exact?

No. It is an estimate. Actual paint needs vary by surface condition, texture, color change, primer use, paint coverage, roller nap, overspray, waste, and application method.