Sherwin-Williams gives a typical coverage range instead of one guaranteed spread rate. That makes a two-ended answer more honest until a selected can provides its own coverage. Surface and application conditions still matter.
- Keep walls, ceilings, trim, and cabinets as separate calculations.
- Use the actual label rate as an optional exact override.
- A user-entered allowance is visible and never implied as a universal norm.
Formula or decision boundary
(gross painted area − excluded area) × coats × allowance factor ÷ 400 to 350 ft²/galCoverage-range interpretation
| Result edge | Coverage used | Meaning |
|---|---|---|
| Lower liquid quantity | 400 ft²/gal | high spread end |
| Higher liquid quantity | 350 ft²/gal | low spread end |
| Label override | chosen product label | product-specific result |
Use the answer
Measure net area
Add each painted face and subtract only openings that will not be coated.
Enter whole coats
Do not hide a primer or a different coating inside the finish-coat count.
Check the label
Use the selected product’s spread rate when it is more specific than the planning range.
Safety and scope
- Assess suspect older paint before sanding or scraping.
- Follow the product label and safety data for ventilation and protective equipment.
Sources and scope
Source links reviewed July 16, 2026. A review date is not the document's publication date.
- Sherwin-Williams: Paint CalculatorNorth America · manufacturer calculator
Actual coverage varies with surface condition, color change, application, and product label.
- National Institute of Standards and Technology: NIST Guide to the SI, Appendix B — Conversion FactorsUnited States · government standard
Code retains exact defining constants where NIST identifies an exact relationship.
- U.S. Environmental Protection Agency: Steps to Lead Safe Renovation, Repair and PaintingUnited States · government guide
Lead rules and certified-contractor requirements may apply; this site does not replace regulatory guidance.