Overview
- The International Conference on Weights and Measures voted on Oct. 15 to stop inserting one-second 'leap seconds' and to allow up to 3,600 seconds of difference to be corrected in a single 'leap hour'.
- The new practice is scheduled to begin in May 2027, prompting international and national time bodies and technology providers to start coordination and standards updates now.
- Leap seconds were introduced in 1972 and have been used 27 times; they have increasingly caused software and network problems because many systems do not handle an extra second cleanly.
- Experts project that the first actual one-hour correction will not be needed for several hundred to roughly 1,000 years, so the policy change is mainly procedural for current systems.
- Adopting a one-hour tolerance aims to reduce risk to communications and computing operations by deferring rare corrections into a single, easily scheduled adjustment similar to existing one-hour civil changes.