Reference time, and how far your own clock has drifted.
What atomicclock.now does
atomicclock.now is a free set of tools that run entirely in your browser. There is nothing to install, no account to create and no limit on how often you use them.
Every page on the site: Atomic Clock Now · Clock Sync Check · UTC Time · TAI vs UTC vs GPS.
Your data stays on your device
Nothing you enter here is uploaded. Times, dates and any figures you type are calculated locally by your own browser, and anything the site remembers between visits — display preferences, saved entries — is stored in your browser's local storage on that device alone. Clearing your browser data removes it. We have no copy.
Free, forever
Every tool on atomicclock.now is free to use. We keep the interface clean and fast so you can get in, convert, and get on with your day. Questions? See our FAQ or the help page, and explore our guides to learn more about the formats we work with.