World time to move to a timescale without leap seconds
International conference on weights and measures backs gradual transition to continuous world time.
Follow-up to: World time faces choice over leap second Thursday, 15 October 2026, 06:58
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The international time standard is changing. The General Conference on Weights and Measures has voted, according to the UK’s National Physical Laboratory, for a timescale in which leap seconds will no longer be inserted.
A leap second is currently used to keep atomic time UTC close to astronomical time. That astronomical time is linked to the Earth’s rotation, which is not entirely regular. Seconds have therefore been added at certain points since 1972.
That system is difficult for digital infrastructure. Computer systems, telecommunications networks, financial markets and electricity grids must use the same time. If an extra second is handled poorly, it can lead to discrepancies between systems or temporary disruptions.
The need for a new approach has grown because the Earth has, on average, started rotating slightly faster in recent years. In theory, this could mean that a negative leap second might be needed in the future: a second removed from the timescale. That would be even more difficult for many systems to process.
According to the National Physical Laboratory, a larger difference between UTC and astronomical time will be permitted from 20 May 2027. The institute says that a difference of up to approximately one hour may arise before intervention is needed again. The link with astronomical time will not disappear; it will continue to be measured and published.
The decision does not immediately change the time on clocks and phones. The practical implementation will take place in stages and require adjustments by organisations that use highly precise timekeeping. For everyday life, a second will remain a second.
The scientific reason for the change is therefore not that the Earth will henceforth rotate at exactly a uniform speed. The main aim is to create a time standard that is more predictable for technical systems. Astronomers and navigation specialists will continue to work with measurements of the Earth’s rotation.
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The scientific explanation and announced transition are based on a national metrology institute and international metrology documentation. The article avoids predictions about the precise consequences for individual systems.
- confirmed The CGPM voted on 15 October 2026 for continuous world time without future leap seconds. — Reported by the National Physical Laboratory. source
- confirmed Leap seconds have been used since 1972 to keep UTC and astronomical time aligned. — National Physical Laboratory. source
- confirmed From 20 May 2027, the difference may rise to approximately one hour. — National Physical Laboratory. source
Editor's note
The decision and intended implementation date were reported by the National Physical Laboratory. The precise technical implementation and final wording of the resolution are still being developed.Sources
- The future of timekeeping — National Physical Laboratory
- Draft Resolutions – 28th meeting of the CGPM — Bureau International des Poids et Mesures
The story so far
- Thursday, 15 October 2026, 06:58 World time faces choice over leap second
- Thursday, 15 October 2026, 20:09 World time to move to a timescale without leap seconds (this article)
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