Guides · Repairs

How to paint a room, starting with how much paint you need

Most of a good paint job happens before the roller: the right amount of paint, walls patched and clean, and edges cut in neatly. Work out the paint from the wall area and the coverage printed on the can, plan for two coats, and the rest is steady rolling.

RoomTag Guides · November 1, 2026

Time

1 to 2 days

Skill

Beginner

Coats

Usually two

1. Work out how much paint

1. Wall area. Add up the length of all the walls and multiply by the ceiling height.
2. Take off doors and windows. Multiply each one's width by its height and subtract them from the total.
3. Divide by the coverage printed on the can (square feet or square metres per gallon or litre). Coverage varies by product and by how rough or porous the wall is, so use the label, not a rule of thumb.
4. Multiply by the number of coats, usually two, and round up. Keep a little left over for touch-ups, labelled with the room and the colour.

Example: four walls of 12 ft and 10 ft in a room with an 8 ft ceiling is (12 + 10 + 12 + 10) × 8 = 352 sq ft. Take off one door and one window, and divide what is left by the label's coverage, then double it for two coats.

• Interior paintEggshell or satin wipes clean in most rooms; matte hides wall flaws. Check the label for the finish and coverage.
• PrimerFor patched spots, bare drywall, stains, or a big colour change.
• Roller frame, covers and trayPick the cover nap the paint can suggests for your wall texture.
• Angled brush, about 2 inFor cutting in along ceilings, corners and trim.
• Extension poleRolls the top of the wall without a ladder.
• Painter's tapeProtects trim and switch plates if you don't have a steady hand.
• Drop clothsCanvas doesn't slide around like plastic does.
• Spackle and a putty knifeFill holes first. See how to patch drywall.

Links open each store's own search page. RoomTag is not affiliated with these stores and earns nothing from these links.

2. Prep

1. Clear and cover. Move furniture to the middle, cover it and the floor, and take off switch plates and outlet covers.
2. Patch and sand holes and dents, then wipe the walls clean of dust and grease.
3. Prime the patched spots and any stains.
4. Tape the trim if you want to, pressing the edge down firmly.

3. Paint

1. Cut in first. Brush a band a few inches wide along the ceiling, corners, trim and around openings, one wall at a time.
2. Roll while the edges are still wet, working in sections from top to bottom, overlapping each pass so you don't leave lines.
3. Let it dry for the time on the can before the second coat, then repeat.
4. Pull the tape while the last coat is still slightly soft, at an angle, and put the covers back once it is dry.

When to call a pro

• The test for lead paint is positive and you need large areas scraped or sanded.
• Ceilings are very high, or the job needs scaffolding over stairs.
• The walls show water damage, peeling in sheets, or mould; fix the cause first.

Related: How to patch a hole in drywall · How to swap a ceiling light for a pendant · The starter tool kit.