20x20 Room Paint Calculator
Need to know how much paint to buy for a 20x20-foot room? At 400 square feet of floor area, this is a large-sized room. Our pre-calculated estimates below show exactly how many gallons you need for two coats of standard paint, with deductions for two doors and 3 windows.
Pre-Calculated Paint Estimate
Low
2.8
gal
Likely
3.2
gal
High
3.6
gal
This range covers 553 square feet with 2 coats. The likely estimate is 2.77 gallons before the selected buffer. If you are buying whole gallons, plan on 4.
Flat or eggshell finish recommended for bedrooms. Low-VOC paint is ideal for better air quality.
View Detailed Breakdown
Based on a 20x20 ft room with 8-ft ceilings, 2 door(s), and 3 window(s). Paint at 400 sq ft/gallon with a 15% buffer.
See the formula and assumptions
Supplies for this room
Picked from the inputs above. Links go to Amazon and we may earn a commission at no extra cost to you. Details
- Interior wall paint You need about 4 gallon(s) of wall paint. Browse paint ›
- 9-inch roller kit with tray A 9-inch roller kit with a tray covers walls quickly. View roller kits ›
- Painter's tape Tape off trim and ceilings for sharp edges. View tape ›
- Canvas drop cloth Cover floors before the first can opens. View drop cloths ›
Rather not do it yourself?
Compare quotes from local painters. Bring your gallon estimate so the bids line up.
Tips for This Room
- A 20x20 room (400 sq ft) benefits from buying a 5-gallon bucket for consistent color and better value.
- Always buy slightly more paint than calculated - extra paint is useful for future touch-ups.
- Two coats are recommended for even color coverage and better durability.
- Test your color on a 2-foot square section of wall before committing to the entire room.
Ready to Start Your Project?
Everything you need to get professional results.
Paint supplies kit
Rollers, brushes, tape, and drop cloths in one box.
Shop suppliesInterior wall paint
Top-rated interior paint for walls.
Browse paintAirless paint sprayer
Saves hours on big rooms and whole-house jobs.
View sprayersProduct links go to Amazon.com
Frequently Asked Questions
How much paint do I need for a 20x20 room?
A 20x20 room with 8-foot ceilings has approximately 640 square feet of wall area before deductions. After accounting for two doors and 3 windows, you will typically need about 4 gallons for two coats of standard paint.
How many square feet of wall space does a 20x20 room have?
A 20x20 room with standard 8-foot ceilings has 640 square feet of total wall area. After subtracting for doors and windows (typically 87 sq ft), the net paintable area is about 553 square feet.
How much paint for a 20x20 room?
A 20x20 room with 8-foot ceilings needs about 4 gallons for two coats of standard paint. This is after deducting for two doors and three windows. Consider buying a 5-gallon bucket for better value.
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