costperdecade

Give it two price-and-lifespan pairs and it works out what each item really costs you over time: cost per decade (price divided by life, times ten), cost per use over any horizon, how many replacements a cheap version burns through, and the year the durable option finally comes out ahead. There’s a —json flag for scripts, a warranty-years input that folds warranty coverage into the math, and it exits 1 when the cheap item actually wins, so it’s honest about losing cases. I kept reaching for this math while writing gear reviews, got tired of redoing it in a spreadsheet, and turned it into the one file. The README links Durable Picks, where the cost-per-decade method started.