How Much Paint Do I Need? (Room-by-Room Chart + Formula)

By RugCalc Editorial Team · Last updated: October 2026 · 9 min read

Quick answer: one gallon of latex paint covers about 350 square feet per coat. For a typical bedroom you'll need about 2 gallons of wall paint plus 1 gallon for the ceiling — for two coats. Here's the exact formula and a room-by-room chart so you buy the right amount the first time.

Step 1: measure the wall area

Before estimating, measure each wall you're painting. The fastest way is to find the room's perimeter (add the length and width, then double it) and multiply by the wall height. For a 12×14 ft room with 8-ft ceilings, that's (12+14)×2×8 = 416 sq ft of wall. If your room has vaulted ceilings, measure each wall face individually and add them up.

You can grab the room's floor area with our square footage calculator, then multiply by ceiling height to get the wall area.

Room-by-room paint chart

These figures assume 8-ft ceilings, standard doors and windows, and two coats on the walls. Your actual amount varies with texture and color change, so add ~10% for touch-ups.

Room	Rough size	Wall paint (2 coats)	Ceiling
Small bedroom	10×10 ft	1–1.5 gal	0.5–1 gal
Standard bedroom	12×12 ft	2 gal	1 gal
Large bedroom	14×16 ft	2.5–3 gal	1 gal
Living room	16×20 ft	3–4 gal	1.5 gal
Dining room	12×14 ft	2–2.5 gal	1 gal
Bathroom	6×8 ft	0.5–1 gal	0.5 gal

The paint formula, explained

Paint is sold by the gallon, and coverage is measured in square feet per gallon. The calculation is straightforward:

Total wall area − doors − windows ÷ coverage per gallon × number of coats = gallons you need

Worked example — a 12×14 ft room with 8-ft ceilings:

• Perimeter = 12 + 12 + 14 + 14 = 52 ft
• Wall area = 52 × 8 = 416 sq ft
• Minus 1 door (21 sq ft) and 2 windows (30 sq ft) = 365 sq ft
• At 350 sq ft per gallon = 1.04 gallons per coat
• Two coats = 2.09 gallons → buy 2 gallons of wall paint

How coverage varies by finish

Not every paint covers the same area. As a rule of thumb, flatter finishes spread further, while glossier, higher-solids paints cover less:

Finish	Typical coverage / gallon	Best for
Flat / matte	350–400 sq ft	Ceilings, low-traffic walls
Eggshell	300–350 sq ft	Living rooms, bedrooms
Satin / semi-gloss	250–300 sq ft	Kitchens, bathrooms, trim
Primer	200–300 sq ft	First coat on bare wall

Walls vs ceiling vs trim

These are three separate calculations. The ceiling uses its own square footage (length × width) and often a flat finish. Trim and doors use the same paint as the walls if you're doing them, but account for them separately — a 4×8 ft door front is about 32 sq ft, and baseboards add up fast. When in doubt, round up to the next gallon. Leftover paint in the can is a feature, not a bug — it's your touch-up supply.

How many gallons by project size

If you're planning a whole room or a bigger job, here's how the numbers scale for two coats on the walls (8-ft ceilings, standard openings):

Project	Wall area	Gallons (2 coats)
Single accent wall	~100 sq ft	1 gal
Small room (10×10)	~300 sq ft	1.5–2 gal
Standard room (12×12)	~350 sq ft	2 gal
Large room (14×16)	~450 sq ft	2.5–3 gal
Studio / small apt	~700–900 sq ft	4–5 gal
3-bed house (walls)	~1,500–1,900 sq ft	8–11 gal

These are wall-paint estimates. Add ~1 gallon per standard ceiling and ~0.5 gallon for trim/baseboards in each room.

Buying & money-saving tips

• Buy the same brand and batch. Different batches of the same color can differ slightly; get enough in one trip to avoid a color-matching hassle.
• Buy 5-gallon buckets for large jobs. For 3+ gallons, a 5-gal bucket usually costs less per gallon than individual cans.
• Prime dark-to-light changes. One coat of tinted primer often beats a third topcoat, and costs less per gallon.
• Keep a labeled can for touch-ups. Write the room and date on the lid and store it upright away from freezing.
• Ask about mistints. Many paint stores sell discounted "mistint" gallons — great for primer coats or utility rooms.

What else affects how much paint you need

Beyond room size, a few things can push your gallon count up or down:

• Ceiling height. Every extra foot of ceiling adds roughly 5–10% to the wall area on a typical room. A 10-ft ceiling room uses noticeably more than an 8-ft one.
• Number of colors. Each color you add means separate cans and more leftover. Two accent walls in a second color usually cost an extra gallon.
• Wall texture. Orange-peel, knockdown, and rough plaster absorb 20–30% more paint than smooth walls.
• Spray vs roller. Spraying wastes a little more overspray than rolling; budget ~10% more if you spray.
• Priming bare drywall. New drywall or patched walls need a primer coat first — figure that as an extra pass over the same area.

Tools you'll need (and what they cost)

Budgeting the supplies up front keeps you from mid-project runs. A typical paint job needs:

• Roller + frame + tray: ~$15–$35
• Trim brushes (2–3 in): ~$10–$25 each
• Painter's tape: ~$5–$10 per roll (you'll want 2–3 rolls for a room)
• Drop cloths: ~$15–$30
• Caulk + spackle for prep: ~$10–$20

These are typical retail ranges; prices vary by brand and store.

Common mistakes

• Forgetting the second coat. If you paint one coat and it looks streaky, you're stuck buying more. Plan for two from the start.
• Not subtracting doors and windows. It's only ~10% of the wall, but over a whole house that's a full gallon or more of waste.
• Ignoring texture. Textured or rough walls drink more paint — drop coverage to ~250 sq ft per gallon.
• Color changes. Covering a dark color with a light one may need a third coat or a tinted primer first.
• Forgetting the ceiling is separate. People estimate "one coat each" and run out halfway across the ceiling — budget the ceiling as its own square footage.
• Rounding down. "I'll save by buying 1.5 gallons' worth in one can" never works. Round up; leftover paint is your touch-up can.