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Construction & DIYGenerated accuracy model review: 2026-05-06
Paint Estimator accuracy and testing
This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.
Formula source
- 1. **Gross Area:** Perimeter (2L + 2W) × Height. 2. **Net Area:** Gross Area - (Doors × 21 sqft) - (Windows × 15 sqft). 3. **Gallons:** (Net Area × Coats) / 350 sqft/gal.
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Room Length: 12 ft
- Room Width: 10 ft
- Ceiling Height: 8 ft
- Doors: 1
- Windows: 2
- Coats: 2
- Coverage: 350 ft²/gal
Expected outputs
- Gallons Needed: 1.72 gal
- Paintable Area: 301 ft²
Known limitations
- This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
- Use the result as a planning estimate unless the calculator page states a stricter purpose.
Assumptions
- The room is treated as a simple rectangle using wall perimeter and ceiling height.
- Door and window deductions use standard opening sizes rather than custom measurements.
- Room dimensions and coverage must be positive, while counts and coats should be zero or greater.
Unit handling
- Room Length accepts values in ft.
- Room Width accepts values in ft.
- Ceiling Height accepts values in ft.
- Doors accepts numeric values.
- Windows accepts numeric values.
- Coats accepts numeric values.
- Coverage accepts values in ft²/gal.
- Gallons Needed is displayed in gal.
- Paintable Area is displayed in ft².
Rounding rules
- Number displays use up to 2 decimal places in the calculator UI.
Version history
1.0.0 - 2026-05-06
Generated accuracy and testing page from the current paint-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Paint Estimator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.