Primer, Ceiling & Trim Paint Calculator
Free primer, ceiling and trim calculator: plan walls, ceiling, trim and primer together.
Private by design: every figure is processed on your device and gone when you leave the page.Try: Room length=12, Room width=12, Wall height=8, Number of doors=2, Number of windows=2, Ceiling coats=1, Trim width=0.5, Wall top coats=2, Waste factor=10, Coverage per gallon=350, Add primer=yes → 312 sq ft, 2 gallons, 144 sq ft, 1 gallon, 44 sq ft, 1 gallon, 4 gallons, 8 gallons
How to use
This tool plans the whole painting job in one estimate. It calculates wall paint from the room dimensions, adds the ceiling as its own area (length times width times ceiling coats), and figures trim from the perimeter times trim width plus casing around doors and windows. If you select primer, it estimates primer for the walls and ceiling together and increases the amount by 20 percent on new drywall.
Buying primer and top coat as one plan avoids the common mistake of running out of primer halfway through a room. The result lists each surface separately and gives a combined total, so your shopping list is complete before you leave the house.
Order the work so primer goes on first on any bare surface, then the ceiling, then the walls, and trim last — that sequence keeps drips off finished areas. The combined total here assumes you buy primer and top coat from the same brand family for color consistency. If you only need the walls, set the primer option to no and the ceiling coats to zero to slim the estimate down to a simple wall job.
FAQ
Do I need primer on new drywall?
Yes. New drywall and bare wood soak up paint, so a primer coat is essential for even color and good adhesion. The calculator below adds primer for new drywall automatically, and increases the estimate by 20 percent to account for absorption.
How do I calculate paint for walls and ceiling together?
Treat the ceiling as its own area: length times width, times ceiling coats, divided by coverage. Walls use the perimeter method. This tool plans both, plus trim, in one estimate so you buy the right amounts together.
How much paint for trim and baseboards?
Trim area is the room perimeter times trim width (about 0.5 ft) plus a little for casing around doors and windows. Trim usually needs two coats. The calculator includes a trim line so the total is complete.