About JetLagCalc
JetLagCalc is the circadian arithmetic: how many days the recovery takes, when to seek and avoid light, and how to start shifting before the flight.
JetLagCalc exists because jet lag advice is folklore ("stay up! drink coffee!") stacked on a circadian system that actually follows rules. Time zones crossed, light timing, and sleep shifts are the levers — and they are calculable.
Every calculator on JetLagCalc shows its formula and its assumptions on the page, so you can check the math, reproduce it in a spreadsheet, or argue with it. Inputs are processed entirely in your browser — nothing is sent to a server, and there are no accounts.
JetLagCalc is an independent, ad-supported project. We are not affiliated with any lender, brand, agency, or the sources we cite (published coaching and industry standards). If a number looks wrong, the contact page reaches a human who fixes it.
What makes JetLagCalc different
- Your numbers never leave your browser. Every calculator on JetLagCalc runs entirely on your device. We never see, store, or transmit the figures you enter — there are no accounts and no server-side processing of your inputs.
- Published methodology. Each calculator page explains the exact formula it uses and the assumptions behind it, so you can check our work or reproduce it in a spreadsheet.
- Free, forever, without a paywall. JetLagCalc is supported by advertising. There is no premium tier, no email gate, and no upsell.
Independence
JetLagCalc is an independent educational project. We are not affiliated with, endorsed by, or acting on behalf of any government agency, lender, insurer, or the organizations whose formulas and public data we reference (such as published coaching and industry standards). All trademarks and referenced standards belong to their respective owners.
Questions, corrections, or suggestions are genuinely welcome — get in touch.