Quick Room Paint Estimator

How to Use the Quick Room Estimator

Enter your room's length, width, and ceiling height in feet, plus your number of coats. This calculator skips door and window deductions entirely, giving you a fast ballpark gallon estimate without needing to measure every opening — useful when you just want a rough number before a supply run.

How the Calculation Works

The calculator derives the wall perimeter from your room's length and width (2 × (length + width)), multiplies by ceiling height to get gross wall area, then multiplies by your number of coats and divides by a fixed 350 sq ft/gallon coverage rate.

Example Calculation

A 12×10 ft room with 9 ft ceilings, 2 coats: perimeter = 2 × (12 + 10) = 44 ft. Area = 44 × 9 = 396 sq ft. Gallons = (396 × 2) ÷ 350 = 2.26, rounded up to 2.5 gallons.

Frequently Asked Questions

How is this different from the Wall Paint calculator?

This estimator skips door and window deductions, so it slightly overestimates paint needed compared to the full Wall Paint calculator — useful for a quick ballpark, but the Wall Paint calculator will give you a tighter number once you know your exact door and window count.

Is it safe to round down instead of up?

Not usually — running out of paint mid-wall means a mismatched batch or an inconvenient store trip. It's generally safer to round up, especially since this estimate doesn't account for texture, uneven coverage, or touch-ups.

Does ceiling paint use the same coverage rate?

This calculator estimates wall paint only. Ceilings are usually painted with a separate flat ceiling paint and calculated separately, using the ceiling's square footage (length × width) rather than wall perimeter.