Free Tool

Paint Calculator

Enter room dimensions, surface type, and coats. Get exact gallon quantities with 5-gal pail breakdown—same math we use in the SiteScope app.

1 Room Dimensions

2 Openings (deducted from paintable area)

1 standard door (3 × 7 ft) −21 sq ft
2 standard windows (3 × 5 ft) −30 sq ft
Total deducted 51 sq ft

Need custom door or window sizes, per-wall openings, or no deduction? Customize in SiteScope →

3 Surface & Paint Details

Rough surfaces absorb more paint, reducing effective coverage per gallon.

From product label. Typical: 350–400 sq ft/gal.

10% brush/roll · 15–20% spray

Leave blank to show gallons only.

4 Primer (optional)

Results

Gross wall area
Openings deducted
Net paintable area
Effective coverage
Finish coats
Waste
Finish
Gallons needed
gallons

Rounded up to the nearest whole gallon. Order in 5-gal pails when possible — typically 10–15% cheaper per gallon.

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Also need wallpaper?
Use the Wallpaper Calculator to get strip count, roll yield, pattern repeat waste, and seam overlap applied automatically.

These estimates use the same formulas as the SiteScope app. Actual quantities depend on wall conditions, installer technique, and product specifications. Always verify with your supplier before ordering.

Skip the calculator entirely

SiteScope does this wall by wall—from a 3D scan.

Scan a room with your iPhone's LiDAR, assign materials to walls in the floor plan view, and SiteScope calculates quantities per wall with openings already deducted. Primer, coats, surface type, and coverage applied automatically per SKU. Export to CSV or PDF before you leave the site.

  • Per-wall breakdown with finish + primer gallons separate
  • Surface type and deep-base coats applied per SKU
  • 5-gal pail breakdown and SKU-level totals in the takeoff tab
  • Your cost, charge, and margin—applied to every line
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