Time Zone Calculator

About the Time Zone Calculator

The time zone converter and meeting planner instantly converts any time between 22 major world time zones and — in meeting planner mode — shows every hour of the day simultaneously across all selected locations, highlighting the windows where all participants are within standard business hours. Remote work has made time zone management one of the most practically important skills in modern professional life. A team with members in Sydney, London, New York, and Singapore spans 20 hours of time difference, meaning there is theoretically no single hour that is within business hours for all four cities simultaneously — and finding the least-worst meeting time requires careful analysis of all participants' local hours at the same moment. Our calculator makes this instant. The time zone converter handles Daylight Saving Time (DST) automatically, which is where most simple time zone tools fail. DST creates two separate complications: first, different countries change their clocks on different dates (the US and Canada transition in March and November, the UK and EU in March and October, Australia in October and April, and many countries including Japan, India, China, Singapore, and the UAE do not observe DST at all). Second, Australia's DST varies by state — Queensland observes no DST while New South Wales, Victoria, South Australia, and Tasmania do, meaning Brisbane is one hour behind Sydney from October to April. Our converter applies the correct DST offset for each location based on the month of the selected date, accurately reflecting real-world time differences rather than the simplified fixed-offset assumption that creates errors in basic calculators. The meeting planner view presents a 24-hour grid showing what time it is in every selected city at each hour in the reference city, with business hours highlighted in green. Meeting slots where every selected city is simultaneously in business hours are identified first, making it easy to find the ideal meeting window. When no such window exists — common for teams spanning Asia-Pacific and the Americas — the tool helps identify the least-inconvenient overlap by showing which cities would need to accommodate an early morning or evening call.

How It Works

All time zone offsets are stored relative to UTC. Conversion: Source local time → UTC → Target local time. UTC = Source time − Source UTC offset. Target local = UTC + Target UTC offset. DST: if the selected month falls in each zone's DST period, the DST offset (typically +1h) is used instead of standard offset. Example: Convert 9:00 AM Sydney (AEDT, UTC+11) on a November date to New York (EST, UTC-5) and London (GMT, UTC+0). UTC = 9:00 AM − 11h = 10:00 PM (previous day). New York = 10:00 PM − 5h = 5:00 PM (previous day). London = 10:00 PM + 0h = 10:00 PM (previous day). Hour difference: Sydney → New York = -16h. Sydney → London = -11h.

Tips & Best Practices

• ✓The hardest time zone combination for business meetings is US West Coast (PT, UTC-8) with Australia and New Zealand. A 3 PM Tuesday call in Sydney (AEDT) corresponds to 9 PM Monday in Los Angeles — there is no single business-hours overlap, and the least-worst option is early morning for one party or late evening for the other.
• ✓Brisbane does not observe Daylight Saving Time while Sydney and Melbourne do. This means Brisbane is 1 hour behind Sydney from October to April, but the same time from May to September. Teams with members in both cities need to track which season they are in.
• ✓The international date line means that Australia and New Zealand are actually in the next calendar day relative to the Americas. A Monday 9 AM meeting in Sydney corresponds to Sunday evening in New York — important for weekly recurring meetings where the day-of-week matters.
• ✓India Standard Time (IST) is UTC+5:30 — a 30-minute offset that catches many schedulers off guard. India does not observe DST. A 9 AM London call is 2:30 PM in Mumbai, and a 3 PM London call is 8:30 PM in Mumbai.
• ✓The best practical approach for recurring global meetings with no ideal overlap is to rotate the burden: alternate between a time that is inconvenient for the Asia-Pacific team and a time inconvenient for the Americas team, so no group always bears the out-of-hours burden.
• ✓Many calendar applications (Google Calendar, Outlook) display events in each attendee's local time automatically when you invite across time zones. However, they do not always handle daylight saving transitions correctly when scheduling weeks in advance — verify critical meetings manually as the DST changeover approaches.
• ✓Working with clients in the UAE and Saudi Arabia: these countries do not observe DST and the UAE is UTC+4 year-round. The effective UK-UAE time difference changes from 3h (winter) to 4h (summer) as the UK transitions DST but the UAE does not.
• ✓Asynchronous work across major time gaps (12+ hours) is often more productive than trying to find meeting overlap. Tools like Loom (async video), Slack with scheduled send, and detailed written briefs reduce the need for real-time meetings and allow each team to work in their optimal hours.

Who Uses This Calculator

Remote work teams scheduling recurring meetings across multiple time zones identify the windows where all participants can attend during business hours. Travellers planning calls home calculate what time it will be for their family when they are in a different country. Project managers coordinating handoffs between offshore development teams in India, Australia, and the UK find the brief windows of overlap. Sales teams targeting international clients plan outreach calls during prospect business hours. Employers considering hiring remote workers in different time zones assess the practical overlap for collaboration. Journalists on deadline in one city reaching contacts in another quickly check whether it is an appropriate time to call.