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Estimate guide

Start at 350 sq ft per gallon. Change it when the can says otherwise.

Use 350 sq ft per gallon as a planning default for many interior walls. Lower it when the surface is rough, porous, or changing color hard. Override it when the product label gives you a better number.

Estimate paint gallons How estimates work
Best for Smooth interior walls

The default is strongest when the surface is clean, coated evenly, and close to standard wall paint conditions.

Override when Texture or color fight the spread rate

Rough walls, porous patches, and strong color changes usually need lower coverage than the default.

Watch next Coats and overage

Coverage alone does not finish the estimate. Coats and the 10% planning buffer still move the buy quantity.

Why it works

One default keeps first-pass paint planning stable

Early store lists and quick room comparisons become easier when one explicit spread rate drives every example and room estimate.

What changes it

Surface condition can beat the default quickly

Rough drywall, patchy repairs, dramatic color changes, or primer-heavy work all pull real coverage down faster than many users expect.

What not to skip

Buffer still protects the final order

Even a good spread rate can still land short if room dimensions, touch-ups, or second-coat reality were tighter than the plan.

How to read the paint coverage rule

Use the label first, then layer the room math and buffer after it.

  1. 01 Start with the can label

    If the product lists a spread rate, that number should beat the generic 350 planning default.

  2. 02 Apply it to the adjusted paintable area

    Openings, included ceilings, and coat count all change the area before gallons are calculated.

  3. 03 Round up after the buffer

    The calculator applies the planning buffer before the final buy quantity so the order stays practical.

Coverage planning table

Use this as a planning baseline, then override the calculator when the product label gives you better information.

Scenario Typical planning range Why it changes
Smooth interior walls 325 to 375 sq ft per gallon Usually the cleanest match for the default estimate.
Textured or porous surfaces 250 to 325 sq ft per gallon Texture and absorption pull the practical spread rate down quickly.
Ceilings and overhead work 300 to 350 sq ft per gallon Application technique and lap control often make ceilings feel less efficient.

Worked example

A 12 by 15 foot room with an 8 foot ceiling, the ceiling included, 50 square feet of openings, and two coats lands at 3.75 gallons to buy after the 10% planning buffer.

Coverage input 350 sq ft/gal Planning default
Room setup 12 x 15 x 8 ft Ceiling included
Final buy quantity 3.75 gallons After 10% buffer

That example works because the 350-square-foot default is paired with explicit coats and a visible overage rule. If the can label says the product covers less, the right move is to lower the coverage input, not to hope the default still fits.

Go back to the calculator with this coverage choice

Use the guide to choose the coverage input, then return to the estimate.

Use this default in the calculator