Timezone Converter

Time zone conversion sounds simple but is error-prone due to DST, half-hour zones, and the International Date Line. Converting 3 PM Eastern Time to Pacific Time means subtracting 3 hours (12 PM PT) — but only when both zones are on standard time or both on DST. During the brief period when Europe has shifted to summer time but the US has not yet sprung forward, the US-UK difference is 4 hours instead of the usual 5. Crossing the International Date Line adds or subtracts a full day: flying from Los Angeles to Sydney, you might depart at 11 PM Thursday and arrive at 7 AM Saturday, having "lost" Friday. UTC (Coordinated Universal Time) serves as the reference point — all zones are defined as offsets from UTC. Converting between any two zones requires converting the source time to UTC first, then to the target zone. This converter handles all these edge cases automatically, including DST transitions for every zone. Enter a date, time, and source zone, and see the equivalent across any number of target zones. All calculations run locally using the JavaScript Intl.DateTimeFormat API.

Time zone abbreviations are notoriously ambiguous. CST could mean Central Standard Time (UTC-6), China Standard Time (UTC+8), or Cuba Standard Time (UTC-5). IST might be Indian Standard Time (UTC+5:30), Irish Standard Time (UTC+1), or Israel Standard Time (UTC+2). BST is both British Summer Time (UTC+1) and Bangladesh Standard Time (UTC+6). For clarity, always prefer UTC offset notation or IANA timezone identifiers (like America/New_York or Asia/Tokyo). IANA identifiers automatically handle DST: America/New_York resolves to EST in winter and EDT in summer. Major business zones to remember: ET (Eastern Time, NYC, UTC-5/-4), CT (Central, Chicago, UTC-6/-5), PT (Pacific, LA, UTC-8/-7), GMT/BST (London, UTC+0/+1), CET/CEST (Paris/Berlin, UTC+1/+2), JST (Tokyo, UTC+9, no DST), AEST/AEDT (Sydney, UTC+10/+11), and IST (India, UTC+5:30, no DST). Military/NATO time uses single letters: Z (Zulu) = UTC, A = UTC+1, B = UTC+2, through M = UTC+12, skipping J.