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RenoCost

Paint Quantity Method

Paint quantity estimates prioritize purchase realism. Calculations convert room geometry into gallons, then round up and add recommended overage.

Model version: RenoCost Pricing Model v3.1 (updated 2026-02-16)

Written by

RenoCost Editorial Team

Content planning, drafting, and usability editing

Reviewed by

RenoCost Methodology Review Team

Formula, assumptions, and quote-comparison review

Last reviewed

February 22, 2026

Methodology reference

Review process: editorial policy · methodology · report an issue

Formula Sequence

  1. 1. Wall area: 2 * (length + width) * ceiling_height
  2. 2. Coverage target: wall_area * coats
  3. 3. Base gallons: coverage_target / 375
  4. 4. Purchase gallons: ceil(base_gallons)
  5. 5. Touch-up reserve: ceil(purchase_gallons * 0.10)
  6. 6. Recommended total: purchase_gallons + reserve

Practical Notes

  • Coverage varies with finish type, wall texture, and color contrast between old and new paint.
  • Textured walls and major color changes often require more paint than baseline assumptions.
  • Buying all paint from the same batch reduces visible color variation between cans.
  • The reserve is intended for future touch-ups and damage repair, not only installation waste.