Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Wait A Second, Let's Not Leap Into This Until June 30!

"I am about to take my last voyage, a great leap in the dark." – Thomas Hobbes, last words

"Look ere ye leap."  – Proverbs, John Heywood

" Nature does not proceed by leaps."  – Philosophia Botanica, Linnaeus

It won't take a leap of faith to be in step with the times at the end of June. All you'll need to do is hold your clocks back a second.

The National Institute of Standards and Technology in Boulder, Colo., and the U.S. Naval Observatory in Washington, D.C., keepers of the nation's two atomic clocks, will join in adding a leap second to the world's time on June 30.

The same adjustment has been made 18 times previously since 1972 (the last one on June 30, 1993), so it's not a leap into the unknown for NIST scientists. Such corrections are decreed by the International Bureau of Weights and Measures in Paris, and all countries with atomic timekeeping systems comply.

Leap seconds are needed to keep super-accurate atomic clocks (such as NIST-7, which neither gains nor loses a second in a million years) in step with the spinning Earth, whose rotation varies several thousandths of a second per day. Since we can't speed up the Earth, we have to slow down the clocks to keep them "in sync." This slowdown is accomplished by stopping them for exactly one second to let the Earth catch up.

This year's leap second will be inserted at 23:59:60 UTC (7:59:60 pm EDT) on June 30, 1994. Use the extra time wisely, perhaps to get a jump on the competition.

As a non-regulatory agency of the Commerce Department's Technology Administration, NIST promotes U.S. economic growth by working with industry to develop and apply technology, measurements and standards.

Released May 24, 1994, Updated November 27, 2017