Question 1

How accurate is this online atomic clock?

Accepted Answer

This clock synchronizes against authoritative Network Time Protocol (NTP) Stratum-1 time servers connected to atomic frequency standards (NIST and BIPM). Local drift is corrected dynamically, maintaining sub-millisecond precision.

Question 2

What is an atomic clock and how does it work?

Accepted Answer

An atomic clock measures the resonant frequency of atoms, most commonly Cesium-133. One second is officially defined by the International System of Units (SI) as 9,192,631,770 oscillations of the microwave radiation corresponding to the transition between two hyperfine levels of the ground state of Cesium-133.

Question 3

Why does my device clock differ from the atomic clock?

Accepted Answer

Consumer computer and smartphone quartz oscillators experience thermal drift and battery fluctuations. Unless continuously synced with an NTP daemon, device clocks can easily drift between 1 and 15 seconds per week.

Question 4

What is the difference between UTC, GMT, and Atomic Time (TAI)?

Accepted Answer

International Atomic Time (TAI) is a uniform time scale based on hundreds of atomic clocks. UTC is the civil standard kept synchronized with Earth rotation by inserting leap seconds. GMT is an astronomical time zone originally centered at Greenwich, London.

NIST-Synchronized Online Atomic Clock

Cesium-133 Frequency Standard

NTP Stratum-1 Protocol

TAI vs UTC & Leap Seconds

Frequently Asked Questions About Atomic Time & NTP Accuracy

Explore Global Time & Related Directories

Precision Horology & Global Time Tools

High-Volume City Time Differences

Global Financial & Metropolitan Capitals