Time Zone Converter
🔒 Runs in your browser
In other time zones
How this time zone converter works
Choose a source zone and type a date and time — that instant is then rendered in every
target city at once. The conversion leans on your browser's built-in IANA time-zone database
through Intl.DateTimeFormat, the same data every operating system ships, so each
city shows the correct UTC offset for that exact date without a single network request.
Daylight saving time, handled automatically
Offsets are not fixed: Bucharest is UTC+2 in winter and UTC+3 in summer, New York swings between UTC−5 and UTC−4. Because the lookup is anchored to the moment you pick, the tool applies the DST rule that was actually in force on that day — no need to remember when the clocks changed.
Reading the day markers
A single instant can land on a different calendar date depending on where you are. When a target city is a day ahead of your source zone it shows +1 day; a day behind shows −1 day. That is the detail that trips up cross-continent scheduling, so it is surfaced next to every time.
Frequently asked questions
How does the converter handle daylight saving time?
It uses the browser's built-in IANA time-zone database through Intl.DateTimeFormat, so each city automatically shows the correct offset for that exact date — summer time or winter time — without any manual switch.
What does the +1 day or -1 day marker mean?
A single instant can fall on a different calendar date depending on the zone. The marker shows whether a target city is a day ahead of or behind your source zone at the chosen moment — handy when scheduling calls across the world.
Which time zones can I add?
A curated list of major world cities is offered by default, including Bucharest, London, New York, Los Angeles, Dubai, Mumbai, Shanghai, Tokyo and Sydney. Your own detected zone is added automatically.
Is any of this sent to a server?
No. All conversions run entirely in your browser using standard JavaScript date APIs. No date, location or setting ever leaves your device.