How Much Paint Do You Need for a Bedroom?
A 12 × 15-foot bedroom with an 8-foot ceiling needs about 1.5 gallons of paint for two wall coats. Round that up to 2 gallons, and set aside the extra paint for touch-ups. At $60 per gallon, that is $120 in paint. Enter your room’s exact measurements in the paint calculator.
How Much Does One Gallon of Paint Really Cover?
Cans say “400 square feet per gallon,” but that assumes a smooth, primed, ideal surface—essentially, a laboratory wall. In real rooms, plan on:
Smooth, primed drywall: 350 sq. ft. per gal.
Lightly textured drywall (orange peel): 300 sq. ft. per gal.
Knockdown or rough texture: 250 sq. ft. per gal.
Bare drywall, first coat: 250 sq. ft. per gal. because it absorbs more paint
Always calculate for two coats unless you are completing a like-for-like refresh.
What Do MaterialCalc Paint Estimates Show?
Across recent MaterialCalc paint jobs, 91% of estimates request two coats, the median wall area is 480 sq. ft., and users add an 8% waste factor so that they have paint left over for scuff touch-ups. Follow that approach, and you will rarely run out midway through a wall.
How Do You Calculate the Paint You Need?
wall_sq_ft = (2 × length + 2 × width) × ceiling_height − door_area − window_area gallons = (wall_sq_ft × coats) ÷ coverage_per_gallon
Deduct 21 sq. ft. for each standard interior door and 15 sq. ft. for each standard window.
How Many Gallons Does a 12 × 15 Bedroom Need?
For a 12 × 15-foot bedroom with an 8-foot ceiling, one door, and two windows:
Perimeter: 2 × 12 + 2 × 15 = 54 ft.
Wall area: 54 × 8 = 432 sq. ft.
Openings: 21 + (2 × 15) = 51 sq. ft.; 432 − 51 = 381 sq. ft. of paintable wall area
Two coats on primed drywall: (381 × 2) ÷ 350 = 2.18 gallons
Buy 2 gallons if you are confident in the coverage rate; buy 3 gallons if the walls have patches.
How Many Gallons of Paint Does Each Room Need?
Room | Typical wall area | Gallons (2 coats) Powder room (5 × 6) | 176 sq. ft. | 1 gal. Bedroom (12 × 12) | 384 sq. ft. | 1.5 gal. Primary bedroom (14 × 18) | 512 sq. ft. | 2 gal. Living room (16 × 20) | 576 sq. ft. | 2 gal. Entire three-bedroom house interior | About 2,400 sq. ft. | 12–15 gal.
What Paint-Estimating Mistakes Should You Avoid?
Ignoring the second coat. One coat looks fine while you are using the roller—until the light hits the wall sideways at 4 p.m.
Skipping primer over patches. Bare joint compound absorbs paint unevenly; coat patches with a primer-sealer first.
Buying paint from different batches. Mixed batches can appear as subtle stripes. Box all cans by pouring them together before you begin.
Guessing how much trim paint you need. A gallon of trim paint covers about 600 linear feet of standard baseboard, so most rooms need only a quart.
Choosing the wrong sheen for the room. Bathrooms and kitchens need satin or semi-gloss; flat paint hides drywall flaws but develops marks in hallways.
How Much Does Interior Paint Cost in 2026?
Contractor-grade interior latex: $28–$40 per gal. (SW ProMar 200 and BM Ultra Spec).
Mid-tier: $45–$70 per gal. (SW SuperPaint and BM Regal Select).
Premium: $75–$110 per gal. (SW Emerald and BM Aura). Premium paint is worthwhile for deep colors and one-coat refreshes.
How Can You Calculate Your Exact Paint Amount?
The paint calculator subtracts doors and windows, converts the result to gallons at your chosen coverage rate, and shows both one- and two-coat totals.