Resources / Paint and finishes

Paint and Finishes: Estimating, Picking Sheens, and Prepping a Room That Lasts

Estimating paint correctly means dividing paintable wall area by 350 square feet per gallon for one coat on primed drywall, choosing sheen based on how much a surface gets touched and cleaned rather than how it looks in the can, and prepping the wall (cleaning, patching, sanding, priming where needed) before the first coat goes on, since most paint jobs that fail early fail from skipped prep, not from a cheap can of paint. A $70 gallon applied over an unwashed, unpatched wall will chip and peel faster than a $25 gallon applied correctly.

This guide covers how to estimate the right amount of paint, which sheen fits which room, and the prep steps that determine whether the finish lasts two years or ten.

Estimating how much paint you need

Direct answer: Add up the linear footage of all walls, multiply by ceiling height for total wall area, subtract roughly 20 square feet per door and 15 square feet per window, then divide by 350 (average coverage per gallon on primed drywall) to get gallons for one coat, and double that for two coats.

Measure the room's perimeter (all four walls added together) in linear feet.
Multiply by ceiling height. A 56-foot perimeter at 9-foot ceilings gives 504 square feet of wall area.
Subtract openings: three windows and a door removes roughly 65 square feet, leaving 439 paintable square feet.
Divide by 350 to get gallons for one coat. 439 divided by 350 is 1.25 gallons. Double for two coats and round up, since paint is sold in full gallons.
Adjust the coverage number down to 250-300 square feet per gallon for unprimed drywall, heavy texture, or a dark-to-light color change. All three cut real coverage by 20-30% versus the standard number.

The mistake that blows up the estimate: using the 350 square-foot figure on a wall going from a dark, saturated color to white or another light color. That transition almost always needs a third coat or a tinted primer first, and skipping that step means running out of paint mid-wall or living with visible color bleed-through.

Choosing the right sheen for each room

Direct answer: Match sheen to how much a wall gets touched or washed, flat and matte for low-traffic walls and ceilings, eggshell and satin for living areas and bedrooms, and semi-gloss or gloss for kitchens, bathrooms, trim, and doors, since higher sheens resist moisture and scrubbing better but show more surface imperfection.

Flat / Matte: best for ceilings and low-traffic adult bedrooms. Hides wall imperfections well but marks easily and is hard to wipe clean without burnishing the finish.
Eggshell: the standard living-room and bedroom sheen, a light shine that's washable enough for normal household use while still hiding minor wall flaws reasonably well.
Satin: a step up in washability from eggshell, works well in hallways, kids' rooms, and family rooms that see more contact and cleaning than a formal living room.
Semi-gloss: the standard for kitchens, bathrooms, trim, and doors, since it holds up to moisture, grease, and repeated wiping. Shows wall imperfections more, so surface prep matters more at this sheen level.
High-gloss: reserved for doors, cabinetry, and accent trim where a hard, reflective, easy-to-clean surface matters more than hiding imperfections, rarely used on full walls.

The mistake that blows up the finish: putting a flat or matte sheen in a kitchen or bathroom because it "looked nice" in the can. Flat sheens can't handle grease splatter or humidity-driven wiping, and the wall will show wear and staining within a year in those rooms regardless of paint quality.

Prepping a room so the finish actually lasts

Direct answer: Clean the walls to remove dust, grease, and grime, fill and sand any holes or cracks, sand glossy trim or previously painted surfaces to give the new coat something to grip, and prime over patches, stains, or major color changes, since paint that goes on top of dirt, gloss, or an unsealed patch fails from underneath even if it looks fine on application day.

Clean first. Wipe walls with a mild soap and water solution, especially kitchens and bathrooms where grease and soap residue build up. Paint doesn't bond to a dirty surface no matter how good the product is.
Patch and sand. Fill nail holes, dents, and cracks with spackle, let it cure fully, then sand flush. An unsanded patch telegraphs through even a top-tier paint once the light hits it at an angle.
Sand glossy surfaces. Any surface with an existing semi-gloss or gloss finish (trim, doors, previously glossy walls) needs a light scuff sand so the new coat has something to grip. Skipping this step is the single most common cause of peeling on trim repaints.
Prime where needed. Bare patched drywall, water stains, smoke stains, and major color changes (dark to light) all need a primer coat first. Skipping primer on a stain means the stain bleeds back through the new paint within weeks.
Tape and protect trim, floors, and fixtures before the first coat, not after cutting in starts. Rushed taping is where most clean edges are lost.

The mistake that blows up the finish: skipping primer over a water stain or a dark-to-light color change to save a step. The stain bleeds through or the old color shows in a faint halo, and the fix is stripping back to prep that should have happened the first time, which costs more in time and material than doing it right at the start.

Quick reference: sheen by room

Room / Surface	Recommended sheen	Why
Ceilings	Flat / Matte	Hides imperfections, no need for washability
Living rooms, bedrooms	Eggshell	Washable enough for normal use, hides minor flaws
Hallways, kids' rooms	Satin	More washable than eggshell for higher-contact areas
Kitchens, bathrooms	Semi-gloss	Resists moisture and grease, wipes clean
Trim, doors, cabinetry	Semi-gloss to High-gloss	Hard, durable, easy-to-clean surface

Get a paint estimate based on your actual walls

Once you have your measurements and sheen choices, run them through MyRemodelCalculator for a photo-based estimate that reflects your real coverage needs, not a flat per-room average.

Start your estimate →

FAQ

How many coats of paint do I actually need?

Two coats is standard for any noticeable color change or a wall in average condition, one coat can work only when painting a very similar shade over a wall already in good condition with no stains or patches.

Do I need primer if I'm painting a similar color?

Not usually, primer is mainly needed for bare patched drywall, water or smoke stains, or a significant color change (dark to light), a same-tone repaint on a clean, undamaged wall can typically skip it.

What sheen should I use in a kids' room?

Satin is the common choice for kids' rooms, it's more washable than eggshell for handling marks and fingerprints while still looking appropriate for a living space rather than a utility room.

Why does my paint job look uneven even after two coats?

Uneven coverage after two coats usually points back to prep, an unsanded patch, a skipped primer coat over a stain, or rolling over a dirty or glossy surface all cause visible unevenness that more paint alone won't fix.

Is it worth paying more for premium paint?

Premium paint generally offers better coverage per coat and more durable washability, but it can't compensate for skipped prep, a $25 gallon applied over a clean, properly patched and primed wall will outperform a $70 gallon applied over dirt or an unsanded patch.