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Interior walls

Paint calculator

Estimate paintable wall area, gallons, primer, material cost, labor range, and a basic shopping list for one room.

Reviewed · May 9, 2026

Home Project Estimates

Paint calculator

May 9, 2026

12 ft by 14 ft room, 8 ft walls, 2 coats.

Paint needed
2.2 gal
344 sq ft paintable wall area
Primer
1.1 gal
Single primer coat
Waste buffer
10%
Built into paint and primer quantity
DIY material total
$137–$264
Paint, primer, and basic supplies
Labor range
$344–$1,032
Directional wall-painting labor
Contractor total
$481–$1,296
Materials plus labor

Shopping list

  • standard interior latex paint2.2 gal
  • Primer1.1 gal
  • Roller covers, tray, brush, tape, drop clothBasic kit

Assumptions

  • 350 sq ft per 1.0 gal coverage
  • 10% waste buffer
  • 21 sq ft per door and 15 sq ft per window deducted
  • U.S. near average; pricing data: U.S. near average pricing

Planning estimate only. Not a contractor quote, engineering advice, or permit review.

Project inputs
U.S. near average
Units
ft
Wall to wall
ft
ft
ea
ea
Estimated result

12 ft by 14 ft room, 8 ft walls, 2 coats.

Paint needed
2.2 gal
344 sq ft paintable wall area
Primer
1.1 gal
Single primer coat
Waste buffer
10%
Built into paint and primer quantity
DIY material total
$137–$264
Paint, primer, and basic supplies
Labor range
$344–$1,032
Directional wall-painting labor
Contractor total
$481–$1,296
Materials plus labor
Textured walls, dark color changes, and porous surfaces can require more paint.

Shopping list

  • standard interior latex paint2.2 gal
  • Primer1.1 gal
  • Roller covers, tray, brush, tape, drop clothBasic kit

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Assumptions in this estimate

  • 350 sq ft per 1.0 gal coverage
  • 10% waste buffer
  • 21 sq ft per door and 15 sq ft per window deducted
  • U.S. near average; pricing data: U.S. near average pricing

Saved estimates

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How this is calculated

  • Wall area is calculated as 2 x (length + width) x wall height.
  • Doors and windows are deducted with standard average areas.
  • Gallons include coats and a 10% waste buffer, then round up to the nearest tenth.

Assumption register

Item Low Typical High Source
Paint coverage 300 350 400 Sherwin-Williams paint calculator
Checked 2026-05-10 · medium confidence
Waste buffer 5 10 15 Sherwin-Williams paint calculator
Checked 2026-05-10 · medium confidence
Standard paint price 34 45 55 Homewyse paint benchmark and retail cross-checks
Checked 2026-05-10 · low confidence

Last reviewed: May 9, 2026. These values are planning defaults, not live prices.

Common mistakes

  • Forgetting primer when covering stains, bare drywall, or a strong color change.
  • Using one-coat math for a two-coat job.
  • Ignoring textured or porous walls.

FAQ

Should you buy exactly the calculated gallons?

Use the estimate as a planning number, then round to practical container sizes before buying.

Does this include ceilings or trim?

No. This MVP calculator estimates interior walls only.

Why show a range?

Paint brand, finish, wall condition, and region all change the final cost.

Limitations

This calculator estimates interior wall painting only. It does not include ceilings, trim, repairs, specialty primers, or exterior work.

This estimate is for planning only. It is not a contractor quote, engineering advice, or permit review.

Next step

Measure once more, compare the result with a real quote or shopping cart, and review the assumptions before buying materials.

Read the DIY vs contractor guide for this project

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