Most interior walls need two coats of paint. One coat can be enough when you repaint a wall the same or a very similar color over paint in good condition. Add a coat of primer first on new drywall, bare wood, stains, glossy or unusual surfaces, and when you make a big change in color.
Every extra coat adds the full wall area to your paint order. The paint calculator has a coats field, so you can compare one, two and three coats before you buy. If the walls need primer first, the primer calculator works out how much for the same room.
Coats of primer and paint by situation
| Situation | Primer | Finish coats |
|---|---|---|
| Same or similar color over sound paint | Usually none | 1 to 2 |
| Any color over a white wall | Usually none; a tinted primer can help | 2 |
| Dark color to a light one | High-hide primer, sometimes 2 coats | 2 |
| Light color to a bold or dark one | Gray-tinted primer | 2, sometimes 3 |
| New or unfinished drywall | Drywall primer, 1 to 2 coats | 2 |
| Bare wood | Primer (oil-based is often preferred) | 2 |
| Ceramic wall tile (not floors or showers) | Adhesion primer | 2 |
| Brick fireplace surround | Masonry primer | 2 |
When one coat is enough
A single coat can work when the new color is the same as, or close to, the old one, the existing paint is clean and sound, and you are using a good-quality paint. Look at the wall in daylight once it is dry. If the color and sheen look even from several angles, you are done.
Even then, many painters roll a second coat on walls that get scuffed or cleaned often, such as hallways and kitchens. Two coats build a thicker, more durable film and hide small differences in how the first coat went on.
Why two coats is the standard
- Even color. The first coat soaks into patched spots and porous areas unevenly. The second evens it out.
- Even sheen. Patches and spackle can look dull through one coat (called flashing), especially in eggshell, satin and semi-gloss.
- Hiding the old color. Some colors, especially yellows, reds and deep tones, hide poorly, and the old color shows through a single coat.
- Durability. A full film thickness stands up better to cleaning and wear.
When to use primer
Primer helps paint stick and seals the surface so it does not soak up the paint unevenly. That often saves a coat of the more expensive finish paint.
- New drywall and plaster. Bare paper and joint compound absorb paint differently. Prime first so the seams do not show through. Unfinished plaster needs a stain-blocking primer.
- Bare wood. Prime to seal the grain and stop tannins from bleeding through light colors.
- Dramatic color changes. A high-hide primer helps when going from dark to light. When going to a bold or deep color, a gray-tinted primer neutralizes the old color and can cut the number of topcoats.
- Stains and repairs. Water stains, smoke and large patches need a stain-blocking primer.
- Slick or unusual surfaces. Glossy paint, ceramic tile, vinyl and brick each need the right primer, sometimes with a light sanding or an adhesion test first.
Is paint-and-primer in one enough?
Self-priming paint works best on smooth, sound walls when the new color is similar to or lighter than the old one. For new drywall, bare wood, stains or a big color change, a separate primer is usually the better choice, and primer costs less per gallon than most finish paint.
How coats change the amount of paint
Paint coverage is per coat. Take a 12 × 14 ft bedroom with 8 ft walls, one door and two windows, which has 365 sq ft of wall to paint (the full calculation is in how much a gallon of paint covers). At 350 sq ft per gallon with 5% extra for touch-ups:
| Plan | Paint to roll | Gallons needed | What to buy |
|---|---|---|---|
| 1 coat | 365 sq ft | 1.10 gal | 1 gallon + 1 quart |
| 2 coats | 730 sq ft | 2.19 gal | 2 gallons + 1 quart |
| 3 coats | 1,095 sq ft | 3.29 gal | 3 gallons + 2 quarts |
| Primer + 2 coats | 365 + 730 sq ft | About 1.5 gal primer + 2.19 gal paint | 2 gallons of primer, 2 gallons + 1 quart of paint |
If you are unsure whether you will need a third coat, buy for two and keep the receipt, or plan a quart of extra. Running out partway through a wall is worse than having a little left over.
Signs you need another coat
- The old color shows through, or the wall looks blotchy in daylight.
- Patched or spackled spots look duller or shinier than the rest (flashing).
- You can see roller marks or lap lines where wet paint met dry paint.
- Corners and edges cut in with a brush look a different shade from the rolled area.
Let the first coat dry and wait for the recoat time on the can before you judge it. Wet paint looks different from dry paint, and rolling a second coat too soon can lift the first.
Tips for fewer coats and an even finish
- Clean and repair first. Wash greasy walls, fill holes and spot-prime the patches.
- Ask for a tinted primer. Primer tinted toward the new color, or gray for bold colors, reduces the topcoats you need.
- Keep a wet edge. Roll from wet paint into dry, finishing a whole wall before taking a break.
- Mix your cans together. Combining all the gallons in a bucket (boxing) keeps the color consistent across walls.
- Save some paint. Keep a little of the final color, labeled with the room, for touch-ups later.
Ready to buy? The paint calculator turns your room size, openings and number of coats into gallons and quarts.
Sources
- Bob Vila: How Many Coats of Primer You Need for the Perfect Paint Job (when to use one or two coats of primer, tinted primer and self-priming paint)
- Sherwin-Williams: Painting FAQs (primer and topcoats for tile and brick, estimating quantity, saving paint for touch-ups)
- This Old House: Decoding the New Low-VOC Paints (self-priming paint, primer on new drywall and gray-tinted primer for bold colors)
- Sherwin-Williams Paint Calculator (coverage per gallon, quart and primer)
