Paint for a 16×20 room

What a 16×20 room usually is

• Large great room
• Finished basement
• Open living-dining
• Large studio or shop

320 square feet with 576 square feet of wall. This is the largest room most homes have, and at this scale the cost of paint has stopped being the main number — the pail, the primer, the trim enamel, the tape, the cloths and the roller covers together often come to as much again. The supplies list below is worth pricing properly rather than estimating.

Buy list for a 16×20 room

The paint is rarely the whole bill. For a 16×20 room with a 72 ft perimeter:

Primer is listed as conditional because it genuinely is. Previously painted walls in good condition, going a similar colour, do not need it. Bare drywall, patched repairs, water stains, or a dramatic colour change all do — and skipping it there costs you an extra finish coat, which is more expensive than the primer was.

This is a two-day paint job

That is hands-on time for one person at an unhurried pace, and it excludes drying. Add two to four hours between coats — the recoat time on the can, not the touch-dry time — so a job this size realistically spans two days. A second person cutting in while the first rolls does not halve the total, but it comes close.

What still changes the gallon count

Four things move the gallon count on a 16×20 room, and they are worth knowing before you buy rather than after:

Notice which of those actually changes the number. Surface texture usually does — a bare or heavily textured wall drops coverage from 350 to about 250 sq ft per gallon, which is enough to add a full gallon. Deducting openings usually does not: a door and two windows come to about 50 sq ft, and after rounding up to whole gallons the saving generally vanishes. That is why this site leaves openings in by default — the small surplus becomes your cut-in buffer and your touch-up paint. Sheen does not change this table — see which paint sheen.

The long walls are the job

A 16×20 room has a longest wall of 20 ft and a proportion of 1.25:1. That matters more than it sounds, because wall area alone does not tell you how the job will go — a 12×16 and a 14×14 room have exactly the same 448 sq ft of wall and the same perimeter, but they paint quite differently.

At 20 ft, the long walls here are past the point where you can comfortably keep a wet edge across the whole run. Lap marks are the risk on this room — the visible stripe you get when fresh paint meets paint that has already started to set. Work in vertical sections roughly a roller-width-and-a-half wide, always rolling back into the wet edge of the last section, and finish the whole wall before you stop. A break halfway along a 20 ft wall shows.

The 1.25:1 proportion means two long walls and two short ones, so budget your time unevenly — the long pair will take noticeably more than half the rolling. It is also worth starting on a long wall while you are fresh and your technique is most consistent.

Worth knowing before you start

Basements deserve one extra check: test for moisture before you paint. Tape a square of plastic sheet tightly to the concrete wall for 24 hours, and if the underside is damp afterwards you have moisture coming through the wall. Ordinary paint over that will blister and peel within a year regardless of how carefully it goes on.

The arithmetic

Wall area = 2 × (16 + 20) × 8 = 576 sq ft; × 2 coats = 1,152 sq ft; ÷ 350 sq ft per gallon (smooth drywall) = 3.29 → round up to 4gallons. Trim and time come from standard rates — 250 sq ft/hour rolling and 60 linear ft/hour cutting in — all documented in how we calculate. The full reasoning is in how much paint do I need?, and if you are weighing it against a quote, see what it costs to paint a room.

Other room sizes

• Paint for a 12×14 room
• Paint for a 12×16 room
• Paint for a 14×14 room
• Paint for a 14×16 room
• Paint for a 15×20 room
• Paint for a 20×20 room

See all room sizes →