Paint Calculator — How Much Paint Do I Need?
Calculate exactly how many gallons of paint you need for your room. Enter your room dimensions and get an accurate estimate in seconds.
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Gallons Needed
Total Wall Area —
Paintable Area (after openings) —
Total Area to Cover (with coats) —
Disclaimer
This calculator provides estimates for planning purposes only. Actual material
requirements may vary based on surface conditions, application method, product
brand, and other factors. Always consult product labels and your supplier for
precise quantities. We are not responsible for material shortages or excess
resulting from the use of this tool.
Assumptions
- Standard interior door opening = 20 sq ft (3'×6'8")
- Standard window opening = 15 sq ft (3'×5')
- One gallon of interior paint covers approximately 350 sq ft
- Result is rounded up to the nearest whole gallon
- Does not account for ceiling painting — walls only
- Textured walls may require 10-20% more paint
Frequently Asked Questions
How much paint do I need for a 12x12 room?
A 12×12 room with 8-foot ceilings has about 384 sq ft of wall area. After subtracting a door and two windows, you'll need about 2 gallons for two coats.
How many square feet does a gallon of paint cover?
Most interior paints cover 350-400 square feet per gallon on smooth walls. Textured or porous surfaces may require more paint.
Should I buy extra paint?
It's wise to buy an extra quart or half gallon for touch-ups. This calculator rounds up to the nearest gallon, which usually provides a small buffer.