Free US quantity worksheet
Paint Calculator for Surface Area, Coats and US Gallons
Measure a rectangular room or enter a gross paintable surface area. Subtract unpainted openings, choose coats and enter the actual label coverage. The result shows US gallons and the count if buying only one-gallon containers.
Starting figures illustrate the calculation. Replace them with verified measurements and the actual product details. Allowances are your choice, not a recommended rate.
Your quantity result
- Net surface area (sq ft)
- 312
- Area multiplied by coats (sq ft)
- 624
- Paint with allowance (US gallons)
- 1.961
- Equivalent US quarts
- 7.845
- If buying only 1-gallon containers
- 2
US gallons, one selected paint and the entered number of coats. The 350 sq ft per gallon example is not a universal product rate. Check the label, surface and finish. Primer, different products/colors, trim and painting suitability need separate planning.
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Count the surface and coats separately
Rectangular-room wall area = 2 × (length + width) × height. Add length × width only if the ceiling uses this same paint and coat plan. Subtract measured unpainted openings once. The manual-area option also expects gross area before the separate opening deduction.
Paint quantity = net area × coats × (100 + allowance %) / (100 × label coverage per coat). Four US quarts equal one US gallon. The whole-gallon result rounds up only for the stated one-gallon-container buying method.
For 312 sq ft, two coats, an entered 350 sq ft per US gallon and a chosen 10% extra allowance, the estimate is about 1.961 US gallons, or two one-gallon containers. Those are worksheet inputs, not a recommended coating system.
Use the selected product and actual surface
BEHR lists 250 to 400 sq ft per gallon per coat for the named ULTRA and PREMIUM PLUS interior products in its buying guidance. This does not make 350 a universal paint rate. Product, surface texture and preparation affect the amount needed.
Calculate separate products, colors, primer and trim separately. The tool does not choose preparation, coats, product suitability or lead-safe work methods. Check the current label and project requirements before ordering or working.