Creative · official-source review · reviewed 2026-10-10
Buying paint by eye leaves you with a half-empty can or a second trip to the store mid-coat.
Turn the wall area, the number of coats, and the coverage on the label into a gallon count.
Home painters and craft makers working on a flat surface who want a plain gallon estimate.
Use the source document or official route that applies to your situation. This guide does not contact another person or verify external information.
Multiply each wall's width by its height, then add them. Subtract large doors and windows.
Plan for the number of coats you will actually apply, usually two for a color change.
Use the coverage on the can label. Thick or absorbent surfaces cover less.
Multiply the wall area by the coats, then divide by the coverage. Round up.
Paint a small patch first. If the coverage is poor, buy more before you start the full room.
The walls are 480 square feet, you plan 2 coats, and the paint covers 350 square feet per gallon. You need 960 square feet of coverage, so buy 3 gallons.
Use your own source and details. The example is not a record about a real person or organization.
American Coatings Association · reviewed 2026-10-10
What this source supports: Coverage rates for paint vary by thickness, substrate, and application; thin acrylic layers cover roughly 100–150 sq ft per gallon.
Source limit: Thick impasto, absorbent surfaces, and thinned paint change coverage dramatically. This is a rough estimate.
These sources support the statements above. They do not show that every person needs this guide. They do not show a specific result.
This guide estimates gallons from the numbers you enter. It does not account for texture, absorbent surfaces, or thinned paint, which change coverage a lot.
Thick impasto, absorbent surfaces, and thinned paint change coverage dramatically. This is a rough estimate.
Use current instructions from the responsible organization. This guide is a planning aid, not an official decision or a substitute for qualified advice.
Turn the wall area, the number of coats, and the coverage on the label into a gallon count.
This App estimates gallons from the numbers you enter. It does not account for texture, absorbent surfaces, or thinned paint.
You enter every number yourself. The sources support the method and the limits. They do not produce a result for your specific case. Keep the original documents next to the sheet you build.
The App computes the worked example with your own numbers, in your browser.
APP 1
Turn the wall area, the number of coats, and the coverage on the label into a gallon count.
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Open Paint Gallons for a RoomThe App runs in this browser. It does not send or save entries. Copy, download, or print only when you choose.
This guide uses short, direct instructions as an ASD-STE100-style writing target. It is not a formal certification.
Companion App: Paint Gallons for a Room. It runs in this browser and does not upload your entries.
This guide is edited for clarity and checked against the sources it links. It is not a substitute for official instructions or qualified advice. A linked source does not show that every person needs this guide.