How much paint do I need for a 15×20 living room?

Data checked October 2026

Short answer

A 15 × 20 ft room with 8-ft walls has 473 sq ft of wall to paint — 2.7 gallons for two coats, so buy 3 gal (about $173).

Wall area: 70 ft of perimeter × 8 ft = 560 sq ft, minus 2 doors (21 sq ft each) and 3 windows (15 sq ft each) = 473 sq ft.
Paint: 473 × 2 coats ÷ 350 sq ft/gal = 2.7 gal → 3 gal, the cheapest can mix at typical prices.
Ceiling too: 300 sq ft × 2 coats needs another 1.71 gal (2 gal).
Trim: 64 ft of 6-in baseboard plus door and window casing is 53 sq ft — 2 qt of semi-gloss covers two coats.
Brand calculators: Sherwin-Williams' says 2.4 gal (400 sq ft/gal); Benjamin Moore's says 3 gal (350 sq ft/gal).
Supplies (roller kit, covers, brush, tape, drop cloth) add about $75.16.

Adjust it to your exact job

Room size

Rooms

Same wall height and paint in every room.

Length

= 15' · 4.57 m

Width

= 20' · 6.1 m

Wall heightfloor to ceiling

= 8' · 2.44 m

Doors & windows

Doors

Windows

What are you painting?

Walls

Ceiling

Trim (baseboards & casings)

Trim area comes off the wall area so it isn't counted twice.

Situation & coats

What's on the walls now?

Two coats is the norm (Sherwin-Williams, Valspar Signature). Benjamin Moore and Valspar Reserve list 1 or 2 coats for a same-color refresh in a premium line.

Topcoats

Primer

Deep or bright color

Reds, yellows, navy: adds a coat unless you prime.

Paint

Wall paint

350 sq ft per gallon per coat — the low end of Sherwin-Williams' and Benjamin Moore's ranges, and the figure Benjamin Moore's calculator uses. Label: 2 coats.

Plan with coverage

sq ft/gal

Per coat. We plan at the low end of the label range so you don't run short.

Buy for the walls

3 gal

2.7 gal for 473 sq ft × 2 coats at 350 sq ft/gal · $173

Wall area to paint: 473sq ft560 sq ft minus 87 sq ft of openings
Ceiling: 300sq ftnot included
All paint & primer: 2.7galwalls
Paint + supplies: $248$173 paint · $75.16 supplies

What to buy for each surface
Surface	Area (sq ft)	Coats	Need	Buy	Cost
WallsTypical latex wall paint · 350 sq ft/gal	473	2	2.7 gal	3 gal	$173

Why brand calculators disagree

Sherwin-Williams' calculator (400 sq ft/gal, 21 sq ft per door, 15 per window) says 2.4 gal for 2 coats; Benjamin Moore's (350 sq ft/gal, always 2 coats, 12 sq ft per window) says 3 gal. We use your product's own label rate and your actual door and window sizes.

Shopping list

3 cans Typical latex wall paint — 1-gal can (walls)$173
1 packs 9 in roller covers, 3-pack, 3/8 in napa fresh cover for each product or color$6.43
1 kit Roller frame & tray kit$21.94
1 brush 2½ in angled sash brushfor cutting in$13.94
1 rolls Painter's tape, 1.88 in × 60 yd (ScotchBlue 2090)146 ft of baseboard and casing to mask$7.88
1 cloths Canvas drop cloth, 9 × 12 ftone per room, moved along the walls$24.97
1 set Lightweight spackle & sanding spongepatch nail holes and dents first

Estimated total$248

Cost estimate

Tap a price to use your store's

Typical latex wall paint, 1-gal can (walls)
3 cans × $typical price — no verified listing
$173
9 in roller covers, 3-pack, 3/8 in nap
1 packs × $
$6.43
Roller frame & tray kit
1 kit × $
$21.94
2½ in angled sash brush
1 brush × $
$13.94
Painter's tape, 1.88 in × 60 yd (ScotchBlue 2090)
1 rolls × $
$7.88
Canvas drop cloth, 9 × 12 ft
1 cloths × $
$24.97

Materials total$248

Online prices checked October 23, 2026 (Sherwin-Williams, Benjamin Moore, Walmart). Tap any price to enter your store's.

Did this answer your question?

Compare

Paint for a 15×20 room by plan (typical 350 sq ft/gal paint)

Plan	Gallons	Buy	Paint cost
Walls, 1 coat (same-color refresh)	1.35	1 gal + 2 qt walls	$104
Walls, 2 coats	2.7	3 gal walls	$173
Walls + ceiling, 2 coats	4.42	3 gal walls + 2 gal ceiling	$288
Walls + ceiling + trim	4.42	2 gal + 2 qt walls + 2 gal ceiling + 2 qt trim	$323
New drywall: primer + 2 coats	4.28	3 gal walls + 2 gal primer	$221
Deep color, no primer (3 coats)	4.05	4 gal + 1 qt walls	$253

How this was worked out

A 15×20 living room has 560 sq ft of gross wall at 8 ft. This is where buying a 5-gallon pail of a line that sells one can start to pay off — compare in the table.

The full method, material data and tips are on the main paint calculator page.

Similar jobs

Other sizes people check

Sources

Data behind this answer

Sherwin-Williams Paint Calculator (help text and AjaxPaintCalculator responses) — results are per coat at 400 (interior), 350 (exterior) and 250 (deck) sq ft/gal; 3×7 ft doors and 3×5 ft windows; trim area = LF × height subtracted from the wall; railings × 0.6, or × 2.0 with spindles; gables = width × peak ÷ 2 · checked October 2026
Benjamin Moore Paint Calculator (calculator code) — walls only, 350 sq ft/gal × 2 coats, 21 sq ft doors and 12 sq ft windows, gallons + quarts · checked October 2026
Sherwin-Williams Emerald Interior — PDS 101.08MAB — 350–400 sq ft/gal at 4 mils wet; drywall: self-prime with 2 coats or primer + 2 coats; drastic color change: prime · checked October 2026
Sherwin-Williams SuperPaint Interior — PDS 101.02A — 350–400 sq ft/gal; primer + 2 coats on new surfaces · checked October 2026
Sherwin-Williams Duration Home Interior — PDS — 350–400 sq ft/gal · checked October 2026
Benjamin Moore Regal Select — TDS N549 — 400–450 sq ft/gal; $84.99/gal online · checked October 2026
Benjamin Moore ben — TDS N626 — 400–450 sq ft/gal, self-priming · checked October 2026
Behr Ultra Scuff Defense Interior — product label (Home Depot-hosted PDF, rev. 09/20) — 250–400 sq ft/gal; tinted primer coat for drastic color changes · checked October 2026
Valspar Signature, Ultra & Reserve interior — product pages — Signature 200–400, Ultra 300–400, Reserve 400 sq ft/gal; fully loaded roller ≈ 9 sq ft · checked October 2026
Glidden Fundamentals & High Endurance Plus — Walmart.com listings — gallon, quart and 5-gal prices, Oct 23 2026 · checked October 2026
Clark+Kensington interior & exterior — Ace Hardware listings — interior 400–450, exterior 350–450 sq ft/gal; satin $42.99/gal, $20.99/qt, $219.99/5 gal (search snapshot Oct 2026) · checked October 2026
KILZ 2 All-Purpose Primer — Walmart.com listing — 300–400 sq ft/gal; $9.97 qt, $23.97 gal, $65 3.5 gal, $94 5 gal · checked October 2026
Zinsser Bulls Eye 1-2-3 — TDS (rev. 02/07/2025) — 400–450 sq ft/gal; practical 450 non-porous / 350 porous (assumes 15% loss) · checked October 2026
Sherwin-Williams Premium Wall & Wood Primer — PDS 108.38 — 400 sq ft/gal at 4 mils wet · checked October 2026
Sherwin-Williams online prices (homeowner product pages) — quart, gallon and 5-gal guest prices, Oct 23 2026; 5-gal pails ≈1% cheaper per gallon · checked October 2026
Painting supplies — Walmart.com listings — ScotchBlue 60 yd $7.88; 9×12 canvas drop cloth $24.97; 3-pack roller covers $6.43; tray kit $21.94; 2½ in sash brush $13.94 · checked October 2026
US EPA — Lead Renovation, Repair and Painting Program — about three-quarters of US homes built before 1978 still contain some lead-based paint · checked October 2026

Short answer

A 15 × 20 ft room with 8-ft walls has 473 sq ft of wall to paint — 2.7 gallons for two coats, so buy 3 gal (about $173).

Wall area: 70 ft of perimeter × 8 ft = 560 sq ft, minus 2 doors (21 sq ft each) and 3 windows (15 sq ft each) = 473 sq ft.

Paint: 473 × 2 coats ÷ 350 sq ft/gal = 2.7 gal → 3 gal, the cheapest can mix at typical prices.

Ceiling too: 300 sq ft × 2 coats needs another 1.71 gal (2 gal).

Trim: 64 ft of 6-in baseboard plus door and window casing is 53 sq ft — 2 qt of semi-gloss covers two coats.

Brand calculators: Sherwin-Williams' says 2.4 gal (400 sq ft/gal); Benjamin Moore's says 3 gal (350 sq ft/gal).

Supplies (roller kit, covers, brush, tape, drop cloth) add about $75.16.

Adjust it to your exact job

Room size

Rooms

Same wall height and paint in every room.

Length

= 15' · 4.57 m

Width

= 20' · 6.1 m

Wall heightfloor to ceiling

= 8' · 2.44 m

Doors & windows

Doors

Windows

What are you painting?

Walls

Ceiling

Trim (baseboards & casings)

Trim area comes off the wall area so it isn't counted twice.

Situation & coats

What's on the walls now?

Two coats is the norm (Sherwin-Williams, Valspar Signature). Benjamin Moore and Valspar Reserve list 1 or 2 coats for a same-color refresh in a premium line.

Topcoats

Primer

Deep or bright color

Reds, yellows, navy: adds a coat unless you prime.

Paint

Wall paint

350 sq ft per gallon per coat — the low end of Sherwin-Williams' and Benjamin Moore's ranges, and the figure Benjamin Moore's calculator uses. Label: 2 coats.

Plan with coverage

sq ft/gal

Per coat. We plan at the low end of the label range so you don't run short.

Buy for the walls

3 gal

2.7 gal for 473 sq ft × 2 coats at 350 sq ft/gal · $173

Wall area to paint: 473sq ft560 sq ft minus 87 sq ft of openings
Ceiling: 300sq ftnot included
All paint & primer: 2.7galwalls
Paint + supplies: $248$173 paint · $75.16 supplies

What to buy for each surface
Surface	Area (sq ft)	Coats	Need	Buy	Cost
WallsTypical latex wall paint · 350 sq ft/gal	473	2	2.7 gal	3 gal	$173

Why brand calculators disagree

Shopping list

3 cans Typical latex wall paint — 1-gal can (walls)$173
1 packs 9 in roller covers, 3-pack, 3/8 in napa fresh cover for each product or color$6.43
1 kit Roller frame & tray kit$21.94
1 brush 2½ in angled sash brushfor cutting in$13.94
1 rolls Painter's tape, 1.88 in × 60 yd (ScotchBlue 2090)146 ft of baseboard and casing to mask$7.88
1 cloths Canvas drop cloth, 9 × 12 ftone per room, moved along the walls$24.97
1 set Lightweight spackle & sanding spongepatch nail holes and dents first

Estimated total$248

Cost estimate

Tap a price to use your store's

Typical latex wall paint, 1-gal can (walls)
3 cans × $typical price — no verified listing
$173
9 in roller covers, 3-pack, 3/8 in nap
1 packs × $
$6.43
Roller frame & tray kit
1 kit × $
$21.94
2½ in angled sash brush
1 brush × $
$13.94
Painter's tape, 1.88 in × 60 yd (ScotchBlue 2090)
1 rolls × $
$7.88
Canvas drop cloth, 9 × 12 ft
1 cloths × $
$24.97

Materials total$248

Online prices checked October 23, 2026 (Sherwin-Williams, Benjamin Moore, Walmart). Tap any price to enter your store's.

Plan

Gallons

Buy

Paint cost

Walls, 1 coat (same-color refresh)

1.35

1 gal + 2 qt walls

$104

Walls, 2 coats

2.7

3 gal walls

$173

Walls + ceiling, 2 coats

4.42

3 gal walls + 2 gal ceiling

$288

Walls + ceiling + trim

4.42

2 gal + 2 qt walls + 2 gal ceiling + 2 qt trim

$323

New drywall: primer + 2 coats

4.28

3 gal walls + 2 gal primer

$221

Deep color, no primer (3 coats)

4.05

4 gal + 1 qt walls

$253