Elapsed Time / Countdown (Time-Zone & Calendar Accurate)
Pick a start date & time and a time zone. The clock will tick every second with DST-safe calendar math.
Seconds enabled. Uses the selected time zone, not your device zone.
Auto-detected:
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How it works & accuracy notes
We compute in the selected time zone using Intl.DateTimeFormat(...).formatToParts to obtain wall-clock components (Y/M/D/H/M/S). We then build UTC “surrogate” dates with Date.UTC(...) and advance them by calendar units (years → months → …) until the next increment would overshoot. This preserves real month lengths, leap years, and Daylight Saving boundaries. We never parse localized strings or rely on Date.toString().