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Paint Calculator

Estimate paintable area, paint volume, and cans with US customary or metric units.

Unit system

Example values loaded. The result updates automatically when you edit area, coverage, or can size.

Area and application

Add width x height for every wall; e.g., two 10 x 8 ft walls = 160 sq ft, or two 3 x 2.6 m walls = 15.6 m² before openings.

sq ft

Number of paint layers applied.

Paint and package

Check the paint label; use a conservative estimate.

sq ft per gallon

Allowance for texture, touch-ups, roller loss, and color changes.

%

Use the package size you plan to buy.

gal

Inputs

Total paintable area
450 sq ft
Coats
2
Coverage rate
350 sq ft per gallon
Waste margin
10%
Can size
1 gal

How to interpret the result

After calculation, the can count shows the minimum quantity for the package size entered. The estimated paint amount shows the calculated volume before rounding up to whole cans.

Common mistakes

  • Using floor area instead of paintable wall area.
  • Forgetting extra coats when covering a dark color.
  • Leaving the waste margin at zero for rough or textured walls.

Method

Formula: total paintable area x coats x (1 + waste margin / 100) / coverage rate. Cans are rounded up by the package size you enter.

Example

Reference examples: in US units, 450 sq ft, 2 coats, 10% waste, and 350 sq ft per gallon give 990 adjusted sq ft and 2.83 gal, rounded to 3 one-gallon cans. In metric units, 42 m², 2 coats, 10% waste, and 10 m²/L give 92.4 adjusted m² and 9.24 L, rounded to 3 cans at 3.6 L each.

Assumptions

Use the coverage printed on the paint label when possible. Texture, primer, color change, roller loss, and application thickness can change the final amount.

Review

Last reviewed: 6/23/2026

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