Time Zone Converter - World Clock & Meetings

Conversion Details

Convert a time between major cities and time zones, with today's daylight saving offsets. Find meeting overlap for remote teams and see a world clock.

Select zones

Enter time

Use planner views

Conversions use the IANA time zone data built into your browser, for today's date. Governments sometimes change their clocks at short notice, and an out-of-date browser keeps the old offset. Confirm exact times with an official source before scheduling something time-critical.

Formulas and sources

Each formula this calculator uses, where it comes from, and what it leaves out. "How it works" shows the same formula with your own numbers.

Converting a time

Source Time (in From timezone) ↓ UTC Conversion (apply offset difference) ↓ Target Time (in To timezone)
Source Time
the time you enter, read on today's date in the From zone
UTC Conversion
the same instant in UTC: the source time minus the From zone's UTC offset
Target Time
that instant plus the To zone's UTC offset

Each zone's offset is read for that instant, daylight saving included, from the IANA Time Zone Database built into your browser. The offset difference shown with the result is the gap between the two offsets, without a sign.

Source: Uses the IANA Time Zone Database [1], which ECMA-262 requires time zone aware JavaScript engines to use [2]. NIST notes that time zone and daylight saving corrections arrive with software updates [3].

A time that is skipped or repeated

A time in the skipped hour is read with the offset from before the change. For example, 2:30 a.m. in New York on March 8, 2026 converts as 3:30 a.m. EDT. A time in the repeated hour is its first occurrence: 1:30 a.m. in London on October 25, 2026 is the earlier one, in British Summer Time.

Source: Uses the JavaScript rule, ECMA-262 §21.4.1.26 [2]. The iCalendar standard reads both cases the same way [4].

Meeting windows

Start times step every 30 minutes, on weekdays in both zones, where the whole meeting fits the workday you set. The Time Slider marks each start hour at which the meeting fits the workday in the From zone and in the To zone.

Source: CalcTrail's own scheduling rule; no publisher.

Sources

  1. Internet Assigned Numbers Authority (IANA). Time Zone Database, Theory and pragmatics of the tz code and data (theory.html). Latest release on October 5, 2026: 2026e of September 29, 2026. A browser's copy can be older.
  2. Ecma International. ECMA-262, ECMAScript 2026 Language Specification, §21.4.1.19 Time Zone Identifiers and §21.4.1.26 UTC ( t ), Note 1. 17th edition, June 2026.
  3. National Institute of Standards and Technology. Daylight Saving Time (DST). Undated page, read October 5, 2026.
  4. Internet Engineering Task Force. RFC 5545, Internet Calendaring and Scheduling Core Object Specification (iCalendar), §3.3.5 Date-Time, form #3. September 2009.

What this calculator does not cover

  • It converts one time on today's date, so a meeting after a daylight saving change in either zone can be an hour different.
  • It uses the time zone data in your browser, which can be older than a government's latest change. The IANA database says of itself that it is not authoritative [1].
  • It does not convert past or future dates, or schedule recurring events.

Sources checked on .

Help

Quick Start Guide

  1. Select zones: Choose From and To time zones.
  2. Enter time: Set the source local time to convert.
  3. Use planner views: Use the Planner and World Clock tabs to find meeting overlap.

Frequently Asked Questions

Each time zone is an offset from Coordinated Universal Time (UTC), and many zones change it for daylight saving time. The converter reads each zone's offset for today from the IANA Time Zone Database built into your browser.
Yes. The Suggested Overlap Windows section lists the next meeting slots, stepping every 30 minutes, that fit your workday range and meeting duration in both zones, skipping weekends. The Time Slider also marks the start hours when the meeting fits the workday in both the From and To zones. Both sit alongside the main converter, with no separate mode.
UTC (Coordinated Universal Time) is the international reference time scale. Each time zone is written as an offset from it: New York is UTC-5 in winter (EST) and UTC-4 in summer (EDT). The converter shows each zone's UTC offset beside it.
The Time Slider (on the Planner tab) plots the To time zone against the From zone on a 24-hour timeline. It shows the local time to the minute and marks your workday, so you can see how work hours in the two zones line up. The Suggested Overlap Windows section complements it by listing the next meeting slots in time order.
The World Clock view shows current times in multiple time zones at once. Add time zones to see their current times simultaneously. This is useful for monitoring times across different locations in real-time.

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