Time Zone Converter
See one moment in every city that matters, with day-offset badges and a meeting-window hint. 100% free, no signup. Everything runs in your browser.
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I built this time zone converter because I kept booking calls across three countries and getting at least one person's morning wrong. Pick a date and time, add the cities you care about, and you see the exact same moment laid out side by side in every zone, with a badge telling you when a city has already rolled into tomorrow or is still stuck in yesterday.
Everything runs in your browser using the IANA zone database your browser already ships with, so nothing you type is uploaded anywhere. There is no signup, no ads pretending to be buttons, and no cap on how many zones you can compare at once.
How to use
- Pick the date and time you want to convert, or leave it set to right now.
- Confirm your reference zone. It defaults to whatever your browser reports.
- Type a city or zone name into the search box and add it to your list.
- Repeat for every place you need. The list is searchable, so London, Sydney or Denver are a few keystrokes away.
- Read the same moment side by side in every zone, and watch for the +1 day or -1 day badges.
- Check the highlighted rows. The best meeting window hint marks every city where the local time lands between 9am and 6pm.
Why use our time zone converter?
The searchable city list is built on the browser's own IANA time zone database, the same reference data that operating systems and programming languages rely on. That matters more than it sounds, because daylight saving rules change constantly. Arizona skips DST, Lord Howe Island shifts by half an hour, and politicians rewrite the rules somewhere nearly every year. The maintainers of the IANA time zone database track all of it, and your browser updates alongside it, so I never have to ship a stale lookup table that quietly rots.
The day-offset badges are the feature I actually built this for. The classic scheduling disaster is not getting the hour wrong, it is getting the day wrong. 7pm Tuesday in San Francisco is already Wednesday lunchtime in Sydney, and a calendar invite that ignores that ruins somebody's week. Every row that crosses midnight gets a clear +1 day or -1 day badge, so the date jump is impossible to miss.
The best meeting window hint saves you the mental gymnastics of scanning ten rows and working out which combination keeps everyone inside working hours. Rows falling between 9am and 6pm local are highlighted, so a workable slot for New York, London and Melbourne jumps out at you. So does the honest news that sometimes no such slot exists, and someone will simply have to take a call in their evening.
Nothing is uploaded, because nothing needs to be. The conversion happens in your browser using data your browser already carries, which is also why the page loads fast and keeps working once open. What I refuse to add: accounts, saved team lists behind a paywall, or a newsletter popup between you and the answer. If you compare the same cities every day, just keep the tab pinned.
If your question is about distance between dates rather than clocks, my date difference calculator counts the days, and the business days calculator counts only the working ones.
Who is this tool for?
Remote teams are the obvious case. If your standup includes Denver, London and Sydney, there is roughly one civilized hour per day and it moves twice a year. I check this page every March and October because the US and UK change their clocks on different Sundays, and for a couple of awkward weeks every recurring meeting drifts by an hour and nobody is sure who moved.
Freelancers and agencies with overseas clients use it to translate deadlines before agreeing to them. When a client says end of day Friday Pacific, that is Saturday morning in London and Saturday evening in Sydney. Knowing that before you say yes is much better than discovering it after.
Developers use it as a sanity check for anything user-facing that mentions a time: launch announcements, maintenance windows, webinar invites. If you are debugging machine timestamps rather than meetings, my epoch timestamp converter converts Unix time in both directions and shows UTC, local and ISO 8601 together.
Then there is the personal stuff: calling parents in another country at an hour that will not wake them, catching a product launch announced in ET, or stepping off a long-haul flight and working out what time your body thinks it is versus what the airport clock insists.
Frequently asked questions
Yes, automatically. The IANA database encodes every zone's DST rules, including historical ones, so a time in January and a time in July both convert correctly even though the offset between two cities can differ between those dates.
Because at your chosen moment, that city's calendar has already flipped to the next date. An evening call from the US to Australia almost always lands tomorrow over there. The badge exists so you write the correct date on the invite.
I highlight rows where the local time falls between 9am and 6pm. It is a deliberately simple rule, not a claim about anyone's actual calendar, but it makes the workable overlap visible in one glance instead of ten comparisons.
No. The zone math runs entirely in your browser using its built-in IANA data. I never see which cities you compare or when you plan to meet.
Yes, pick any date. Historic and announced future DST rules are part of the zone database, so a date next July converts as accurately as one this afternoon, barring a government changing the rules between now and then, which does happen.
Search for the nearest major city or the zone name itself, like America/Chicago or Europe/Berlin. IANA zones are named after representative cities, so your town shares its zone with a bigger neighbor.
For scheduling purposes they are the same clock. UTC is the modern technical standard, GMT is the older name that survives in British usage. The converter works from precise UTC offsets either way. If you need working days rather than clock times, the business days calculator picks up where this leaves off.