Interior Painting Cost Calculator

1. Enter the project scope. Set the number of rooms and total wall area in square feet. If you have not measured yet, a standard bedroom is about 400 sq ft of wall area and a living room is about 600-800 sq ft.

2. Assess the surface condition. Good condition means light cleaning and minimal prep. Fair means some patching, sanding, and spot priming. Poor means heavy prep work like skim coating, scraping, or dealing with wallpaper removal.

3. Choose paint quality and coats. Budget paint covers about 350 sq ft per gallon, standard about 400, and premium about 400 with better hide. Two coats is standard for most color changes. Three coats may be needed for dark-to-light transitions.

4. Add extras. Check any additional services like trim, ceilings, doors, or wallpaper removal. Each adds labor hours and materials to the estimate.

5. Set your labor rate and markup. Enter your billable rate per painter per hour and your materials markup percentage. The calculator builds the total estimate and shows your margin.

Materials are calculated from area and coverage. Paint coverage runs about 350-400 sq ft per gallon depending on quality. Primer covers about 300-350 sq ft per gallon. The calculator figures gallons needed, multiplies by price per gallon, adds supplies (tape, drop cloths, rollers), then applies your markup.

Labor is the biggest line item. Interior painting runs about 350 sq ft per hour for walls with a roller. Prep adds 20-50% depending on condition. Trim work runs about 200 sq ft per hour. The crew size determines elapsed time on site but not total labor hours charged.

Target 35-45% gross margin. If the calculator shows you below 30%, increase your rate or markup. Interior work should carry higher margins than exterior because equipment costs are lower and weather is not a factor.

Building a quote after the walkthrough. You have measured the rooms, assessed the surfaces, and the customer wants a number. Plug in the details and have a professional estimate ready in minutes.

Comparing options for the customer. Run the calculator with standard paint, then again with premium. Show the customer both price points. The difference is usually smaller than they expect, which helps upsell to better products.

Training new estimators. New team members often underestimate prep time or forget to include primer. This calculator forces them to account for every cost category so nothing gets missed in the quote.