A 10 × 12 room needs about 3 gallons
Using these planning assumptions, the room has 345 sq ft of paintable wall area after standard openings. At 350 sq ft per gallon with a 10% waste allowance, the exact estimate is 2.17 gallons. We recommend buying 3 gallons — see the calculator result panel for the optimal container combination.
A realistic 10 × 12 project
Raising a 10 × 12 room from 8- to 9-foot walls adds 44 gross sq ft per coat. After standard openings, the paintable wall area is 345 sq ft; two coats and 10% extra require 2.17 gallons and round to three.
How this preset differs from the standard two-coat walls estimate
This comparison changes only the condition named in the page title. Both scenarios use one 21 sq ft door shortcut, two 15 sq ft window shortcuts, 350 sq ft/gal, and a 10% allowance, so the quantity change remains auditable.
| Scenario | Modeled surface | Exact paint | Whole-gallon purchase |
|---|---|---|---|
| Two coats, 8 ft walls, ceiling excluded | 301 sq ft walls | 1.89 gal | 2 gal |
| This page: 2 coats, 9 ft walls | 345 sq ft modeled surface | 2.17 gal | 3 gal |
| Difference before rounding | +0.28 gal | Container rounding can magnify or hide a small volume change. | |
The extra wall height changes paintable area on every wall and every coat; measure the actual height rather than relying on the preset.
What is distinctive about this size?
Nine-foot walls often exceed comfortable reach from the floor. Include safe ladder or extension-pole access in the plan, and keep a continuous wet edge where the upper and lower roller passes meet.
The modeled remainder is about 0.83 gallon. That reserve is useful because tall-wall touch-ups are inconvenient; retain the batch instead of assuming a later can will match exactly.
Calculation for this room
| Room perimeter | 44 ft |
|---|---|
| Gross wall area | 396 sq ft |
| Door and window deduction | 51 sq ft (one door + two windows) |
| Coats | 2 |
| Calculated paint | 2.17 gal |
Tips for a 10 × 12 room
For a small room with taller-than-standard walls:
- Remove or cover furniture before painting — aim for a clear 3-foot workspace around each wall.
- Paint the ceiling first if included, then work top-down on walls to catch drips.
- Cut in edges with a 2½-inch angle brush before rolling for clean lines at corners and trim.
- If this is a frequently used room, choose a washable paint finish (eggshell or satin) for easier cleaning.
Before buying paint
This result is a starting point, not a substitute for the product label. Textured walls, fresh drywall, unsealed patches, and dramatic color changes reduce effective coverage. Measure oversized doors and windows separately, and calculate trim or closets as separate surfaces.
- Use the actual coverage printed on your selected paint can.
- Keep the 10% allowance for touch-ups and application loss.
- Prime new drywall, repairs, stains, or glossy surfaces when required.
- Mix multiple cans together ("boxing") before painting to ensure consistent colour.
What changes this estimate?
A one-foot increase in wall height adds 44 sq ft per coat. Adding the ceiling contributes 120 sq ft per coat. Use the calculator above for unusual openings, different coat counts, or a lower coverage rate for textured or porous surfaces.
Related room sizes
Compare all common room-size paint estimates →
Estimates are for planning; product instructions and field measurements take priority.