PaintJobCalc

For homeowners and painters

Paint Coverage Calculator

Work out how much paint to buy from room dimensions or surface area. Use one calculation for each product and color.

These values are an example. Change them to describe your project.

Calculate from room dimensions

One rectangular room, measured in feet. Apply replaces only the gross area; it keeps the door and window deductions below.

I already know the surface area

If it uses a different product, calculate the ceiling separately.

Set up your calculation

Surface area before door/window deductions. For a room: perimeter × wall height. (ft²)

(ft²)

(ft²)

Make the numbers yours

($ / gal)

Advanced assumptions

Editable starting values. Match production rates to your process and check the products you will use.

Per-coat product coverage. Check its technical data sheet and adjust for the surface. (ft² / gal)

(%)

USD · square feet · US gallons

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Starting example3 gallonsView breakdown

Local option in Minnesota

In the Twin Cities west metro?

Request a written estimate from PaintCrafters for interior or cabinet painting.

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PaintJobCalc, Colors on Walls, PaintCrafters, and Painters Log share ownership. Outside the area, take your summary to a local painter.

A number you can explain.

Gallons = net surface area × coats × (1 + waste %) ÷ product coverage. Round up for each product and color.

Our methodology & assumptions

Worked example with the starting values

3 gallons

Net paintable area
333 ft²
Paint before rounding
2.09 gal
Purchase cost
$135.00
  1. (420 − 42 − 45) = 333 ft² of surface.
  2. 333 ft² × 2 coats × (1 + 10%) ÷ 350 ft²/gal = 2.09 gal.
  3. Round up to 3 whole US gallons at $45.00/gal.

Before you buy paint

Do I enter wall area or floor area?

Enter the surface you will actually paint. For a rectangular room, wall area is 2 × (length + width) × height. A 12 × 10-foot room with 8-foot walls has 352 ft² of wall area before subtracting openings.

Does this include primer or different colors?

This calculation covers one finish product and color. Calculate primer and other colors separately using their own coat count and product coverage.

Which coverage rate should I use?

Use the coating manufacturer's technical data sheet, then adjust for texture, porosity, application method, and your experience. The starting value is an example, not a product specification.

Estimating framework: Painting Contractors Association. This tool's starting values are editable examples, not rates published by PCA.

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