Curtain Calc Pro

Physics-based coverage model: accounts for side/top overlap geometry to give an accurate blackout percentage.

Curtain Calc uses a geometric coverage model to calculate how effectively a curtain panel blocks light from a given window.

CALCULATION MODEL The engine computes direct-cover area minus an edge-leak penalty. The penalty is derived from the difference between the curtain's actual overlap and the user's target overlap on both side edges and the top. The result is a dimensionless coverage ratio (0–1), displayed as a percentage.

INPUT PARAMETERS • Window width & height (cm) • Curtain panel width & height (cm) • Desired side overlap (cm, each side) • Desired top overlap (cm)

OUTPUT • Coverage percentage with color-coded rating • Recommendation: whether curtain width or height needs to increase

HISTORY & RE-USE Calculations are persisted via UserDefaults. Each record can be named, browsed in a list, and reloaded into the calculator as a prefill.

LOCALIZATION English and Simplified Chinese, runtime-switchable without restart.

PRIVACY Zero network activity. Zero data collection. No third-party SDKs.