Hey Product Hunt! 👋 I built Cold Plunge Calc because I was tired of two things: Random numbers on social media — "Stay in for 3 minutes!" (Based on what? Whose water temperature?) "Free" apps that are just funnel pages for $4,000 cold plunge tubs So I made something different: ⏱️ It calculates your safe time based on your water temperature, experience, and goal 🧪 Every claim links to an actual study (Harvard, PubMed, Cell Reports) 🔒 Your data never leaves your browser. No signup, no tracking 🌐 7 languages, fully free, no paywall The core insight comes from Dr. Susanna Søberg's research: regular cold-water swimmers naturally accumulate about 11 minutes per week across 2–3 sessions. The app builds you a progressive plan toward that target. Happy to answer questions! 🧊

Cold Plunge Calc

Stop guessing your cold plunge time. Free & science-backed.

Stop guessing your cold plunge time. Free & science-backed.