Free Time Zone Calculator — Convert World Times Fast

UTC — Coordinated Universal Time — is the international reference point from which all other time zones are measured. It does not observe daylight saving time, which makes it a stable baseline. Zones to the east of the prime meridian run ahead of UTC (positive offsets) and zones to the west run behind it (negative offsets). For example, Tokyo is UTC+9 and New York is UTC-5 in winter.

Daylight saving time (DST) shifts clocks forward by one hour during the warmer months in many countries, effectively changing a zone's UTC offset until clocks fall back in autumn. Not all regions observe DST — Japan, India, and most of Africa do not — and those that do switch on different dates, which means the gap between two cities can vary by an hour or two depending on the time of year.

While most time zones are whole-hour offsets from UTC, several countries use half-hour or even 45-minute offsets. India uses UTC+5:30 so that the entire country shares a single zone without straying too far from solar time. Nepal uses UTC+5:45, and several Australian states use UTC+9:30 for similar geographic reasons. These unusual offsets are why simply adding or subtracting whole hours is not always sufficient for accurate time zone conversion.