How to Measure Wall Area

Wall area is the length of each wall multiplied by its height, summed, minus the openings. Accurate measurement is the foundation of every paint, drywall, and wallpaper estimate. This calculator handles a single wall or an average wall with standard windows and doors — measure each wall separately and repeat for full rooms.

Painting Estimates

One gallon of paint covers approximately 350–400 sq ft per coat. Most repaints need two coats, so plan one gallon per 175 sq ft of net wall area. Higher-quality paints cover more; textured walls and drastic color changes absorb more. This calculator includes a conservative one-coat gallon count.

Drywall Requirements

Standard drywall panels are 4×8 feet (32 sq ft). Divide net area by 32 and round up, then add about 10% for cutting waste. Panels run horizontally on walls to reduce seam count. For a 149 sq ft net wall, plan on 5–6 sheets before waste — this calculator reports the raw count.