Hammer CalculatorPainting & Wallcovering
7 of 7 calculators are live. Everything else below is on the roadmap — check back as more launch.
Figure out how many gallons of paint, primer, or rolls of wallpaper you need for walls, ceilings, and trim. These calculators factor in coverage rates, coats, and openings so you buy the right amount the first time.
Quick Tips
- One gallon of paint covers roughly 350–400 sq ft on smooth surfaces — cut that to 250–300 sq ft for textured walls.
- Always prime bare drywall and patched areas; skipping primer leads to uneven sheen and poor adhesion.
- Subtract half the area of large openings (windows, doors) from your total — small openings aren't worth deducting.