Cost Estimate Methodology

Verified Interior Painting calculator

The base model multiplies paintable wall area by the preserved national range of $2–$6 per square foot, with $2.75 used as the typical walls-only planning point. If sanding and patching is selected, it adds the separately sourced $0.50–$0.75 per square foot allowance. It does not apply a ZIP, city or state multiplier.

Breakdown

The labor allocation is derived from the source-reported 75%–95% share; it is not observed contractor pricing. No public paint-dollar estimate is shown because available gallon prices lack a consistent current product, quality, primer, tax and supplies scope. The unexplained residual stays internal and is not relabeled as materials, overhead or profit.

General worksheet

Project area × (your material rate per square foot + your labor rate per square foot) = entered-cost total. This separate worksheet uses rates supplied by the homeowner and does not present them as market data.

Review and limitations

The national installed range relies primarily on one commercial marketplace dataset and remains MEDIUM confidence. An independent estimating publication provides methodological context but does not corroborate this complete whole-project range. Treat the result as a broad planning range, not an authoritative national benchmark. Verified records retain original ranges, normalization steps, assumptions, source URLs, reviewer and review deadline. Expired records fail closed.