The 180 degree meridian where the calendar date changes, and how the real line zigzags around it.
How this tool works
The map draws the 180 degree meridian, the nominal opposite of the Prime Meridian. The actual International Date Line is a political line that deviates from 180 degrees to keep countries on a single date: it swings east around Kiribati, west of the Aleutian Islands, and east of Samoa and Tonga. Only Russia and Fiji have land that the 180 degree meridian itself crosses. The Diomede Islands in the Bering Strait sit less than 4 km apart on opposite sides of the line, with a time difference of 21 hours in winter.
What you can do with it
- See where the 180 degree meridian runs and which land it touches
- Read how and why the real date line deviates from it
- Use the Diomede Islands example to explain the date change vividly
- Understand why Kiribati and Samoa moved their side of the line
Why use it
The date line is one of the most misunderstood lines on the map because the astronomical meridian and the political line are different things. This page shows the meridian and explains the deviations rather than pretending they are the same line.