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Construction & DIYGenerated accuracy model review: 2026-05-06
Wallpaper 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. **Wall Area** = Wall Width × Wall Height. 2. **Roll Area** = Roll Width × Roll Length. 3. **Usable Area** = Roll Area × 0.85 (assuming 15% waste for matching patterns/trim). 4. **Rolls** = Wall Area / Usable Area.
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Total Wall Width: 12 ft
- Wall Height: 9 ft
- Roll Width: 21 in
- Roll Length: 33 ft
Expected outputs
- Rolls Needed: 3
- Wall Area: 108 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
- Wall width is the combined width of the walls being covered, measured in feet.
- Roll width is entered in inches, roll length is entered in feet, and all dimensions must be positive.
- The calculator applies a fixed 15% waste factor and does not model custom pattern repeats or special layout tricks.
Unit handling
- Total Wall Width accepts values in ft.
- Wall Height accepts values in ft.
- Roll Width accepts values in in.
- Roll Length accepts values in ft.
- Wall 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 wallpaper-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Wallpaper.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.