How we calculate
Investment = purchase + accessories + financing interest. Monthly savings = how often you replace a habit × (outside price − home cost). Months to break even = investment ÷ monthly savings. If savings are zero or negative, we show Never.
Defaults are scenarios you can override. Your real bills always beat our presets.
Privacy
Every calculator runs in your browser. Inputs stay on your device (optional localStorage per tool). We do not run accounts or server-side ledgers.