Interior Guide

Interior finishing estimates cover drywall, paint and trim — three material counts from one set of room measurements.

Measure the Room

Note each wall's length and height plus the ceiling length and width. Subtract nothing for small openings; larger windows and doors come out.

Wall area = perimeter × wall height

Drywall Sheets

Sheets = wall + ceiling area ÷ 32 (for 4×8 sheets)

Add 10-15% for cuts. Count corner and edge care — inside and outside corners use separate runs of joint treatment.

Paint Gallons

Gallons = total paintable area ÷ coverage per gallon ÷ coats

One gallon typically covers 350-400 sq ft per coat. Walls, ceilings and trim are often painted separately with different products — estimate them separately.

Trim and Moldings

Measure linear feet of baseboard and casing.
Add door and window casing per opening.
Account for corners that need miter and coping cuts.

Related Calculators