A Cold Plunge Timer & Ice Bath Tracker for Any Cold Source
Kelvin is a hardware-agnostic cold-exposure companion — a gorgeous plunge timer, a session log with real history, streaks and a calendar heatmap, a breathwork trainer, and adaptation insights. It works with any cold source — ice bath, cold shower, lake, or chest-freezer tub — with no hardware, no pairing, and no $5,000 tub. Kelvin owns the practice, not the tub.
What it does:
- Plunge timer — breath-up rounds, a plunge countdown with a first-30s cold-shock breathing coach, and a guided warm-up
- Session log — water temperature, cold source, and post-plunge clarity, in a tap or two
- Streaks & calendar heatmap — current and longest streak, total time-in-cold, longest plunge, and weekly minutes
- Breathwork trainer — box breathing and Wim-Hof-style rounds, with a hard safety lock near water
- Free safety guardrails — cold-shock and afterdrop guidance, too-long and too-cold exposure warnings, and contraindication warnings
- Works with any cold source — ice bath, shower, lake, or tub; no hardware required
- Local-first & private — offline, no account, your data never leaves the phone
How It Works
⏱️ The Plunge Timer
One guided flow, every session: breath-up rounds, a plunge countdown with a first-30s cold-shock breathing coach to ride out the gasp reflex, and a guided warm-up afterward. A real timer that works on any cold source.
📒 Session Log & History
Log water temperature (°C), cold source, and post-plunge clarity — in a tap or two. The basics the category leader still misses: a session log and history that actually work.
🔥 Streaks & Heatmap
A calendar heatmap and streak tracking keep you honest: current and longest streak, total time-in-cold, your longest plunge, and weekly minutes banked. Watch the practice add up.
🌬️ Breathwork Trainer
A guided box-breathing trainer and Wim-Hof-style rounds to prep for the cold — the trainer won't start until you confirm you're on dry land. Train your breath, not your luck.
🛟 Free Safety Guardrails
Cold-shock and afterdrop guidance, too-long and too-cold exposure warnings, contraindication warnings, and a dry-land check before breathwork. Safety the whole category ignores — free, never paywalled.
🔒 Private & Offline
No account, no login, no cloud. Every session lives in a local database on your phone and opens instantly — even at a frozen lake with no signal. Your data never leaves the device.
A Look Inside
Made for Every Cold Source
🧊 New to the Cold
- Start safely with the Beginner ramp protocol and the first-30s cold-shock coach
- Pick a source — ice bath, shower, lake, or tub — and just start
- Free safety guardrails on every session, never paywalled
🏃 Athletes & Recovery
- Run contrast (sauna → cold) and athletic-recovery protocols
- Track temperature-by-duration tolerance and time-in-cold banked
- Watch your cold-capacity curve and coach digest with Kelvin+
🌬️ Breathwork & Wim-Hof
- Box breathing and Wim-Hof-style rounds in a dedicated trainer
- A dry-land check before breathwork — never breath-hold in or near water
- Pair breathwork with the plunge timer for a complete practice
Kelvin+
Kelvin's core — the plunge timer, the cold-shock safety coach and guardrails, and the session log — is free forever, and no card is needed to explore. Kelvin+ adds insight and ambition, and runs 100% on-device: adaptation insights — your cold-capacity curve and a coach digest, a rule-based summary of your own numbers with a next-week step. History, streaks, and CSV export stay free. Billing is store-managed — cancel anytime in the App Store or Google Play. No dark-pattern trials; we literally can't trap you.
Annual
Best value — works out to about $1.67/month, billed yearly.
Monthly
Flexible month-to-month access to Kelvin+.
Lifetime
A single one-time purchase — no subscription, yours to keep.
Prices may vary by region and are shown in the app at the time of purchase. All three options unlock the same Kelvin+ features. Manage or cancel a subscription anytime in your device's App Store or Google Play subscription settings. See our Terms for full subscription details.
What is Kelvin?
Kelvin is a cold plunge timer and ice bath tracker for iPhone and Android from Adelyons Software LLC. It guides each session with breath-up rounds, a plunge countdown with a first-30s cold-shock coach, and a warm-up, then logs water temperature, cold source, and clarity — offline, with no account and no hardware.
It works with any cold source: an ice bath, a cold shower, a lake, or a chest-freezer tub. The plunge timer, the cold-shock safety coach and guardrails, and the session log are free forever; the optional Kelvin+ upgrade adds adaptation insights: a cold-capacity curve and a coach digest.
Cold plunge guides
Practical, plain-language answers to the questions people ask before their first plunge — and after their fiftieth.
- How long should you stay in a cold plunge?
- What temperature should a cold plunge be?
- Cold plunging for beginners: how to start safely
Frequently asked questions
What does the Kelvin app do?
Kelvin times and tracks cold-exposure sessions. It runs a guided flow of breath-up rounds, a plunge countdown with a first-30s cold-shock breathing coach, and a guided warm-up, then records the session in a log with streaks, total time-in-cold, and a calendar heatmap.
Do I need a special tub or any hardware to use Kelvin?
No. Kelvin is hardware-agnostic — there is nothing to pair and no tub to buy. It works with any cold source, including an ice bath, a cold shower, a lake, or a chest-freezer tub.
Is Kelvin available on iPhone and Android?
Yes. Kelvin is available on the App Store for iOS and on Google Play for Android.
Is Kelvin free, and what does Kelvin+ cost?
Kelvin's core — the plunge timer, the cold-shock safety coach and guardrails, and the session log — is free forever, and no card is needed to explore. Kelvin+ is $3.99 / month, $19.99 / year, or $39.99 once for lifetime access, and billing is store-managed so you can cancel anytime.
Does Kelvin work offline?
Yes. Because every session is stored on the phone, the timer, log, breathwork trainer, and insights all work with no internet connection, and the app opens without a login. That matters at a frozen lake with no signal.
Where is my cold plunge data stored?
Only on your device. Sessions, water temperatures, durations, cold sources, clarity ratings, and your health answers live in a local database on your phone. There is no account and no cloud backend, and your session data never leaves the device.
What safety features does Kelvin include?
Kelvin's safety guardrails are free and never paywalled: cold-shock and afterdrop guidance, too-long and too-cold exposure warnings, contraindication warnings, and a dry-land check before breathwork. Kelvin is a timing and self-tracking tool, not medical advice — consult a doctor before starting cold exposure.
How do I delete my Kelvin data?
Delete individual sessions in the app, clear the app's data from the app or your device settings, or uninstall the app to permanently remove everything it stored locally. There is no server-side copy for anyone to delete.
Privacy First — Your Data Stays on the Phone
Kelvin is built local-first. Here's exactly how it works:
- No account, no cloud, no server. You don't sign up or log in. There is no backend that receives your session data — nothing to leak and nothing to fail.
- Your data never leaves the device. Sessions, water temperatures, durations, cold sources, clarity ratings, and health answers are stored only in a local database (SQLite) on your phone.
- Rule-based insights, not AI. The optional Kelvin+ coach digest is a template engine over your own logs — no model, no download, no network.
- You share, not us. CSV exports are generated on your device and shared only if and when you choose.
- One billing helper. The only data that leaves your phone is purchase data, handled by Apple, Google, and RevenueCat to validate Kelvin+, and, if you use Invite a friend, an invite code with an anonymous install id. Neither includes your session or health data.
For complete details, see our Privacy Policy and Terms of Service.