Exterior House Paint and Primer Calculator
Estimate exterior wall paint, primer, containers, waste, and editable coating cost after subtracting doors and windows.
How to use the exterior paint calculator
- Measure the actual project. Break irregular work into separate sections and record finished dimensions consistently.
- Enter the core measurements. The quick view focuses on project geometry; add or subtract sections where the calculator supports multiple areas.
- Review purchasing assumptions. Open Advanced inputs to replace example prices, waste, coverage, density, pack size, minimum order, or delivery assumptions with current project information.
- Calculate and verify. Review the formula, limitations, whole-unit rounding, product instructions, and supplier requirements before purchasing.
Key inputs covered: Finish coats, Paint coverage per coat, Paint container size, Paint container example price, Texture and application allowance, Include one primer coat, Primer coverage, Primer gallon example price, Wall length, Average wall height, and additional project-specific assumptions.
Result coverage: The exterior paint calculator reports 6 separate quantities so the primary estimate and its supporting purchase or planning values can be checked together.
How the estimate works
Gross exterior wall area minus entered openings is multiplied by finish coats and allowance, then divided by editable coverage; paint containers and optional primer round up separately.
A 30 x 10 ft wall with 55 ft2 of openings has 245 ft2 of net paintable area.
Assumptions, rounding, and limitations
Dimensions are treated as finished measurements. Only deductions and allowances entered above are included. Decimal measurements display to two places; purchase quantities round up when a whole container or piece is required.
- Measure gables, dormers, trim, soffits, doors, and specialty surfaces separately when they use different products or colors.
- Coverage changes with texture, porosity, color change, application method, weather, and the selected coating.
- Follow current product instructions for preparation, primer, compatible substrates, temperature, drying, access, ventilation, and cleanup.
Sources and review
These references support unit conversions and selected planning assumptions. Product instructions and local requirements control the actual project.
Last reviewed: 2026-10-09
Editorial process
BuildPlanCalc publishes the formula, editable assumptions, limitations, and supporting references so the estimate can be checked rather than treated as a black box. See the calculation and review methodology, or report a correction.
Frequently asked questions
Are the results exact?
No. Results are planning estimates based on the dimensions and assumptions entered. Confirm product coverage, site conditions, and ordering rules with the supplier.