What is the International Date Line?
The International Date Line is the line, roughly along 180° longitude in the Pacific, where the calendar date changes. Cross it going west and you skip ahead a day; going east, you repeat a day. It zigzags around island nations so each country keeps a single date.
Key facts
| Location | Roughly 180° longitude, mid-Pacific |
|---|---|
| Earliest time zone | UTC+14 (Line Islands, Kiribati) |
| Latest time zone | UTC−12 (Baker and Howland Islands, uninhabited) |
| Total spread | 26 hours |
| Kiribati moves the line | Effective January 1, 1995 |
| Samoa skips a day | December 30, 2011 |
| Three dates at once | From 10:00 to 12:00 UTC each day |
Why there has to be a date line
Travel east around the world and you set your watch forward an hour every 15 degrees. After 24 zones you've added a whole day, and would arrive home a day ahead of everyone else. Ferdinand Magellan's crew discovered the reverse in 1522: after sailing west around the world, their carefully kept log was a day behind the date in Spain. The date line is where you correct for this.
Why it zigzags
The 180° meridian runs mostly through open ocean, which is why it was a convenient place for the change. Where it would split a country, the line bends. It swings east around Russia's Chukotka peninsula, west of the Aleutian Islands of Alaska, and far east around Kiribati. The line has no international legal status; each country simply chooses which side to be on.
Kiribati's big jump
Kiribati's islands straddle 180°, so for years its eastern and western islands were a day apart, with only four shared business days a week. From January 1, 1995, the government moved its eastern islands to the west side of the line. That created UTC+14 in the Line Islands, the earliest time zone on Earth and the first place to see each New Year.
Samoa's missing Friday
In 2011, Samoa moved to the west side of the line to align with trading partners Australia and New Zealand. The country went from Thursday, December 29 straight to Saturday, December 31, 2011. Friday, December 30 never happened there. Neighbouring American Samoa stayed on the other side, so the two Samoas, about 100 km apart, are now 24 hours apart: same clock time, different dates.
Three dates at once
Because local time on Earth spans 26 hours, from UTC−12 to UTC+14, there are briefly three different calendar dates in use. That happens every day between 10:00 and 12:00 UTC: it's already the next day at UTC+14 while it's still the previous day at UTC−12.
Questions people ask
Do you lose a day crossing the date line?
Flying west across it, the date jumps forward a day. Flying east, you live the same date twice. Your body doesn't gain or lose any time; only the calendar changes.
Where is the first place to see New Year?
Kiribati's Line Islands, such as Kiritimati (Christmas Island), at UTC+14.
Is the date line the same as 180° longitude?
Mostly, but it bends east and west around island groups and Russia so no country is split between two dates.
Sources
Last updated October 18, 2026. Found an error? Tell us.