The date line in practice: how itineraries lose or gain a day

How the international date line works, why Kiribati and Samoa moved it, and how to stop lost or doubled days from creeping into itineraries.

View full page

Kiribati once skipped a day, Samoa skipped another in 2011, and the line itself has no legal status. A short, factual tour of the Pacific date line and what it means for dates on an itinerary.

By Traviology · Published 2026-10-21

In late December 1994 the people of eastern Kiribati went to bed on Friday 30 December and woke up on Sunday 1 January. Saturday was gone. The president had decided it was time the country shared a single calendar date.

Hold onto that. The date line sounds like a fixed, official thing. It isn't.

A line that nobody legislated

NOAA describes the international date line as the boundary between two consecutive calendar dates, established in 1884 and running roughly along 180 degrees longitude. Cross it going west and it's one day later. Cross back and you've "gone back in time", in NOAA's words.

The same page adds that the line has no legal international status, and that countries are free to choose which date they observe. That's why it zigzags around eastern Russia and Alaska's Aleutian Islands.

Two moves worth remembering

The first was Kiribati. Its islands were split by the line for decades, so the western half was always a day ahead of the eastern half, and the two had only four shared working days a week. From 1 January 1995 the line was redrawn around the country's eastern edge.

The second was Samoa and Tokelau, at the end of 2011. To improve trade and travel links with New Zealand and Australia, both moved to the Asian side of the line. Thursday 29 December 2011 was followed by Saturday 31 December.

A Utrecht University history of the date line makes a point agents should care about. Many maps and atlases still show the old position, and many websites on time zones give out-of-date information. If your client is looking at a map they found online, the map may be wrong.

Where it bites in an itinerary

We think the date line causes fewer problems than people fear, but the problems it does cause are annoying ones.

Flights that cross it can land on a different calendar date than the one on which they departed, in either direction. Hotel check-in dates can look wrong to a client who counts nights on their fingers. A tour "on the 14th" can turn out to be a day earlier than the traveller expects.

So we'd do three small things. Write both local dates on the itinerary for every flight that crosses the line. Count hotel nights from the arrival date at the destination, not from the date of departure. And say it out loud on the call: "You'll leave on the 12th and land on the 14th."

The other time quirk: Iceland

Not everything weird about time is in the Pacific. Royal Museums Greenwich notes that GMT is the legal time in Britain in the winter and the name of the time zone used in some countries in Africa and western Europe, including Iceland all year round. For a UK client that means Iceland is an hour behind in summer and level in winter, because the UK clocks change and Iceland's don't.

The same page says GMT was the international standard of civil time from 1884 until 1972, when UTC took over.

What we couldn't verify

We haven't checked any airline timetable for a specific date-line crossing, and we haven't confirmed the exact UTC offsets for Samoa or Kiribati from an official source, so none appear here. If a client is flying to the Pacific, check the airline's own itinerary and a current time-zone database.

Sources

• What is the international date line? (NOAA National Ocean Service)

• A History of the International Date Line: Kiribati and Samoa adjustments (Utrecht University)

• What is Greenwich Mean Time (GMT) and why does it matter? (Royal Museums Greenwich)

Checked October 2026.