Time Zone Converter

Last updated: 2026-06-02

How to Use the Time Zone Converter

Pick the city you are converting from, enter the local time there, and pick the city you are converting to. The converted time appears instantly, along with a label showing whether it lands on the same day, the next day, or the previous day.

You never enter a UTC offset. Each city already knows its offset, and the calculator looks up whether Daylight Saving Time is in effect on the date you choose — so a conversion to New York automatically uses EST in winter and EDT in summer, with no guesswork on your part.

Why the Date Matters

The gap between two cities is not always constant. New York is 5 hours behind London in January, but only 4 hours behind in July. The reason is Daylight Saving Time: both regions move their clocks forward in spring and back in autumn, but on different weekends, so for a few weeks each year the usual offset is shifted by an hour.

Because the calculator computes each city's offset from the date you enter, it stays correct across these transitions. Change the date from January to July and you will see the offsets update. This is the single most common source of timezone mistakes — a meeting booked an hour off because someone used the "winter" difference in summer.

How the Conversion Works

Under the hood, the conversion is offset arithmetic, modulo 24 hours:

$T_{\text{target}} = (T_{\text{source}} + (O_{\text{target}} - O_{\text{source}})) \bmod 24\text{h}$

where $O_{\text{source}}$ and $O_{\text{target}}$ are each city's UTC offset for the chosen date. The modulo-24 step makes the result wrap correctly across midnight, and the day-shift label tells you when the converted time falls on a different calendar day.

Determining the offset for a date means resolving Daylight Saving Time. The calculator does this by deriving each region's transition days from the date — for example, US clocks change on the second Sunday of March and the first Sunday of November, while the EU changes on the last Sundays of March and October. Southern-hemisphere regions such as Australia and New Zealand run the opposite way, with summer time spanning roughly October to April.

Standard UTC Offsets

For reference, here are the standard (winter) offsets of the cities in the list. Where a city observes Daylight Saving Time, the calculator adds one hour automatically during the DST season — you do not add it yourself.

Region	Standard offset	Observes DST?
Los Angeles, Vancouver	UTC−8	Yes (US/Canada)
Denver	UTC−7	Yes (US/Canada)
Chicago	UTC−6	Yes (US/Canada)
New York, Toronto	UTC−5	Yes (US/Canada)
São Paulo, Buenos Aires	UTC−3	No
London, Lisbon, Dublin	UTC+0	Yes (EU)
Paris, Berlin, Madrid, Rome	UTC+1	Yes (EU)
Athens, Helsinki	UTC+2	Yes (EU)
Moscow, Istanbul, Nairobi	UTC+3	No
Dubai	UTC+4	No
Mumbai (India)	UTC+5.5	No
Kathmandu (Nepal)	UTC+5.75	No
Bangkok, Jakarta	UTC+7	No
Singapore, Hong Kong, Shanghai	UTC+8	No
Tokyo, Seoul	UTC+9	No
Sydney, Melbourne	UTC+10	Yes (Australia)
Auckland	UTC+12	Yes (New Zealand)

Cities such as India (UTC+5.5) and Nepal (UTC+5.75) sit on half- and quarter-hour offsets; the calculator handles these exactly.

Practical Uses

Remote and hybrid work

Scheduling a recurring standup across New York, London and Berlin is the classic case. Because the three regions change their clocks on different weekends, the offsets between them drift for a couple of weeks twice a year. Entering the actual meeting date keeps every conversion honest.

Travel planning

Landing in Singapore at 06:00 local and wondering whether it is a reasonable hour to call home? Convert the arrival time to your home city and read off both the time and whether it is still the same day there.

Coordinating live events

Product launches, streams, sports broadcasts and market opens all happen at a fixed instant that lands at different local times around the world. Convert once and distribute the local times with confidence.

A Note on Accuracy

The calculator models Daylight Saving Time at the level of the transition day, which is correct for ordinary scheduling. The only moment it cannot resolve precisely is a time that falls inside the one-hour transition window itself (the early hours of a "spring forward" or "fall back" morning), where clocks are briefly ambiguous everywhere.

If your city is not in the list, choose another city in the same time zone with the same DST rules — for example, pick Berlin for Frankfurt, or New York for Boston. The conversion depends only on the time zone, not the specific city. For historical dates far in the past, note that some regions have changed their DST rules over the years; the calculator uses today's rules.

Frequently Asked Questions (FAQ)

Does this handle Daylight Saving Time automatically?

Yes. Each city is converted using its correct offset for the date you enter. For cities that observe Daylight Saving Time — most of the US, Canada, Europe, Australia and New Zealand — the calculator works out whether DST is in effect on that date and adjusts by one hour automatically. Change the date across a transition weekend and you will see the offset shift. Cities that do not observe DST (such as Tokyo, Shanghai, Dubai and most of South America) keep a constant offset.

My city is not in the list — what do I pick?

Choose any city in the same time zone with the same Daylight Saving Time rules. For example, for Frankfurt or Milan pick Berlin or Rome (Central European Time); for Boston or Miami pick New York (US Eastern Time); for Kolkata or Bengaluru pick Mumbai (India). The conversion depends only on the time zone, not the specific city.

Why does the calculator ask for a date?

Because the offset between two cities can change depending on the time of year. New York is 5 hours behind London in January but only 4 hours behind in July, because the two regions start and end Daylight Saving Time on different weekends. Entering the date of your meeting or call ensures the conversion reflects the offsets that actually apply that day.

What is the difference between UTC and GMT?

For everyday practical purposes, UTC and GMT are the same — both represent the time at 0° longitude. The technical difference is that GMT is a time zone (used by the UK in winter) while UTC is an atomic-clock-based time standard. The offsets shown here are relative to UTC.