Why do dates sometimes differ between countries?

When the reference instant crosses midnight in another zone, we show the correct local calendar date there. That is expected—not an error.

Which country should be the reference?

Pick whichever side owns the meeting invite. The math is symmetric: the tool converts one absolute instant to every selected zone.

Does live mode follow my device clock?

Live mode anchors on the current UTC instant and projects it using each country's zone rules. Your device clock supplies the starting instant.

COMPARATOR

World time comparator

Select up to four countries, set a reference date and time, and see the exact instant in each place.

When it is 01:43 in United States, in Japan it is 14:43.

Reference country

Date

Time

Live time

Times below update when you change the reference date and time.

United States

America/New York

Reference

01:43

Tue, 1 Sep

—

Japan

Asia/Tokyo

14:43

Tue, 1 Sep

Difference vs. reference+13h

About the time zone comparator

The comparator answers a precise question: if it is a given date and time in one country, what is the exact same instant elsewhere? Unlike adding fixed hour offsets in your head, we apply IANA rules so daylight saving and regional exceptions stay correct.

How to compare time zones

Add at least two countries using the search control.
Choose a reference country and set its local date and time (or enable live mode).
Review equivalent local times in every row, including date rollovers.
Adjust the reference or swap countries until you find a workable meeting window.

Example: Madrid and Tokyo

Suppose you want a call when it is 10:00 in Madrid. Add Spain and Japan, set Spain as reference with 10:00 on your chosen date, and read the matching time in Tokyo—often late afternoon or evening. Always confirm on the actual meeting date because DST may differ.

Comparator FAQ

Why do dates sometimes differ between countries?: When the reference instant crosses midnight in another zone, we show the correct local calendar date there. That is expected—not an error.
Which country should be the reference?: Pick whichever side owns the meeting invite. The math is symmetric: the tool converts one absolute instant to every selected zone.
Does live mode follow my device clock?: Live mode anchors on the current UTC instant and projects it using each country's zone rules. Your device clock supplies the starting instant.