PaintCalc

PaintCalc turns "how much paint do I need?" into an exact shopping list. Add a room's walls and its doors/windows, and the app computes the real net paintable area — gross wall area minus every opening — instead of a rough eyeball estimate. The number of coats isn't something you guess or type in: it's computed live from how different your old wall color actually is from the new paint color. Pick both colors and the built-in ContrastMeter reads the real luminance and hue difference between them and recommends 1 to 4 coats, flagging when a primer coat is needed first for high-contrast repaints (like painting a dark wall a light color). Same-family repaints get a quick single-coat estimate; drastic changes get an honest higher count instead of a paint job that still shows the old color through two coats. From there, PaintCalc converts net area, coverage rate and coat count into liters needed, then rounds that up into a real shopping list of can sizes (1L, 2.5L, 5L, 10L) — the same way a hardware store clerk would recommend — and totals the cost from your price per liter. A dedicated Stats screen tracks paint volume and spend across your projects: liters by recent project, area by room category, a 12-week activity heatmap, and a callout for your biggest and most expensive project. Key features: • Wall and opening (door/window) entry with automatic net paintable area • Color-contrast-driven coat count via the ContrastMeter, with primer warnings for high-contrast repaints • Coverage-rate-based liters calculation, rounded to a real can-size shopping list (1L/2.5L/5L/10L) • Total paint cost from price per liter • Room category presets and quick-entry chips for common wall/opening sizes • Stats screen with liters trend, category breakdown, activity heatmap, and top-project callouts • Fully offline — all projects and colors stay on your device