Measure and MendStart measuring

Paint

Ceiling paint

Ceilings are easier to measure as horizontal sections than as part of wall perimeter. Keeping each room separate also prevents a stair opening or unpainted feature from disappearing inside a whole-floor estimate.

First answer

For each rectangular ceiling section, multiply length by width, add the sections, multiply by coats, and divide by the cited 400-to-350-square-foot coverage range.

Run the calculator

Formula or decision rule

sum of ceiling section length × width − excluded ceiling openings; then × coats ÷ 400 to 350 ft²/gal
  • Use the same unit for every dimension before adding areas.
  • The paint calculator accepts a pre-measured net area.
  • A product label can narrow or replace the typical planning range.

Ceiling section worksheet

Ceiling section worksheet
SectionArea expressionInclude?
Main rectanglelength × widthYes
Bay or alcoveits own length × widthAdd
Open stairwellopening length × widthSubtract
Skylight not paintedopening length × widthSubtract

Work through the project

  1. Break the plan into rectangles

    Measure each ceiling plane or section rather than forcing an L-shaped room into one rectangle.

  2. Record exclusions

    Subtract true openings such as an open stairwell, not fixtures whose small footprint is normally painted around.

  3. Plan the work order

    Finish ceiling prep and coating before the walls so drips and edge corrections do not undo finished wall work.

Safety and scope

  • Use a stable platform rated for the task rather than standing on furniture.
  • Stop and assess textured or suspect older coatings before disturbing them.

Sources and scope

Source links reviewed July 16, 2026. A review date is not the document's publication date.

  1. Sherwin-Williams: Paint CalculatorNorth America · manufacturer calculator

    Actual coverage varies with surface condition, color change, application, and product label.

  2. National Institute of Standards and Technology: NIST Guide to the SI, Appendix B — Conversion FactorsUnited States · government standard

    Code retains exact defining constants where NIST identifies an exact relationship.

  3. U.S. Environmental Protection Agency: Steps to Lead Safe Renovation, Repair and PaintingUnited States · government guide

    Lead rules and certified-contractor requirements may apply; this site does not replace regulatory guidance.