CGPM abolishes leap seconds starting May 20, 2027

The 28th General Conference on Weights and Measures (CGPM) in Versailles ended the insertion of leap seconds to keep UTC aligned with Earth's rotation. From May 20, 2027, the drift between UT1 and UTC may reach 3600 seconds — up to a 'leap hour'.

• Leap seconds were introduced in 1972, with 27 added in total
• The last leap second was inserted on December 31, 2016
• UT1 and UTC may now diverge by up to 3600 seconds
• The resolution takes effect on May 20, 2027