{
  "id": "time-zone-meeting-planner",
  "version": "d1f8b45690d0",
  "status": "published",
  "name": "Time Zone Meeting Planner",
  "question": "Time zone meeting planner",
  "summary": "Finds the time on a date when the same working hours overlap in up to 5 time zones, and shows it on each zone’s clock.",
  "category": "days",
  "subcategory": "time-and-hours",
  "url": "https://www.acalculator.org/days/time-zone-meeting-planner",
  "markdown": "https://www.acalculator.org/days/time-zone-meeting-planner.md",
  "kind": "function",
  "method": "For the date in your time zone, take your working hours as a span of moments (UTC); for every other zone, take its working hours on each of its local dates around that date; the overlap is the part of your span inside a span of every other zone, shown on each zone’s clock from the browser’s IANA time zone data.",
  "assumptions": [
    "Every zone uses the same working hours, from the start time to the end time on its own clock; the end must be later in the day than the start (no overnight shifts).",
    "The date is a date in your time zone (the first zone). Your working hours that day are compared with every other zone’s working hours on any of its own dates, so another zone’s part of the overlap can fall on the day before or after, which its date shows.",
    "A zone’s working hours on a date run from the first moment its clocks show the start time that day to the first moment after that when they show the end time. When the clocks skip a time (spring forward), the moment they jump stands in for it; when they repeat an hour (fall back), the working hours include the repeat.",
    "Weekends and holidays are not left out: check the weekday shown for each zone.",
    "Each zone shows the overlap on its own clock as “Mon, Oct 19, 9:00 AM to 11:00 AM”, with the end date too when the overlap crosses midnight on that clock, and several overlaps joined by “; ”. The overlap length is in hours and minutes (“2 hours 30 minutes”, “0 minutes” when there is none).",
    "Offsets and daylight saving come from the browser’s IANA time zone data (tzdata 2026a when this page was checked). Dates from 2000 to 2040 work."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "zone1": {
        "title": "Your time zone",
        "description": "The first time zone; the date is a date in this zone (IANA name).",
        "type": "string",
        "enum": [
          "UTC",
          "America/Adak",
          "Australia/Adelaide",
          "Asia/Almaty",
          "America/Anchorage",
          "Pacific/Apia",
          "Europe/Athens",
          "Pacific/Auckland",
          "Atlantic/Azores",
          "Asia/Baghdad",
          "Asia/Bangkok",
          "Asia/Shanghai",
          "Europe/Berlin",
          "America/Bogota",
          "Australia/Brisbane",
          "Europe/Brussels",
          "America/Argentina/Buenos_Aires",
          "Africa/Cairo",
          "America/Cancun",
          "Atlantic/Cape_Verde",
          "America/Caracas",
          "Africa/Casablanca",
          "Pacific/Chatham",
          "America/Chicago",
          "Asia/Colombo",
          "Australia/Darwin",
          "America/Denver",
          "Asia/Dhaka",
          "Asia/Dubai",
          "Europe/Dublin",
          "America/Edmonton",
          "Australia/Eucla",
          "Pacific/Fiji",
          "Pacific/Guam",
          "America/Halifax",
          "America/Havana",
          "Europe/Helsinki",
          "Asia/Ho_Chi_Minh",
          "Asia/Hong_Kong",
          "Pacific/Honolulu",
          "Asia/Kolkata",
          "Europe/Istanbul",
          "Asia/Jakarta",
          "Asia/Jerusalem",
          "Africa/Johannesburg",
          "Asia/Kabul",
          "Europe/Kaliningrad",
          "Asia/Karachi",
          "Asia/Kathmandu",
          "Pacific/Kiritimati",
          "Europe/Kyiv",
          "Africa/Lagos",
          "America/Lima",
          "Europe/Lisbon",
          "Europe/London",
          "Australia/Lord_Howe",
          "America/Los_Angeles",
          "Europe/Madrid",
          "Asia/Manila",
          "Pacific/Marquesas",
          "Australia/Melbourne",
          "America/Mexico_City",
          "Europe/Moscow",
          "Africa/Nairobi",
          "America/New_York",
          "America/St_Johns",
          "America/Nuuk",
          "Pacific/Pago_Pago",
          "Europe/Paris",
          "Australia/Perth",
          "America/Phoenix",
          "Atlantic/Reykjavik",
          "America/Regina",
          "Asia/Riyadh",
          "Europe/Rome",
          "America/Puerto_Rico",
          "America/Santiago",
          "America/Sao_Paulo",
          "Asia/Seoul",
          "Asia/Singapore",
          "Europe/Stockholm",
          "Australia/Sydney",
          "Pacific/Tahiti",
          "Asia/Taipei",
          "Asia/Tashkent",
          "Asia/Tehran",
          "America/Tijuana",
          "Asia/Tokyo",
          "Pacific/Tongatapu",
          "America/Toronto",
          "America/Vancouver",
          "Asia/Vladivostok",
          "Europe/Warsaw",
          "America/Whitehorse",
          "America/Winnipeg",
          "Asia/Yangon",
          "Asia/Yekaterinburg",
          "Europe/Zurich"
        ]
      },
      "zone2": {
        "title": "Time zone 2",
        "description": "Another time zone to meet with (IANA name), or None.",
        "type": "string",
        "enum": [
          "none",
          "UTC",
          "America/Adak",
          "Australia/Adelaide",
          "Asia/Almaty",
          "America/Anchorage",
          "Pacific/Apia",
          "Europe/Athens",
          "Pacific/Auckland",
          "Atlantic/Azores",
          "Asia/Baghdad",
          "Asia/Bangkok",
          "Asia/Shanghai",
          "Europe/Berlin",
          "America/Bogota",
          "Australia/Brisbane",
          "Europe/Brussels",
          "America/Argentina/Buenos_Aires",
          "Africa/Cairo",
          "America/Cancun",
          "Atlantic/Cape_Verde",
          "America/Caracas",
          "Africa/Casablanca",
          "Pacific/Chatham",
          "America/Chicago",
          "Asia/Colombo",
          "Australia/Darwin",
          "America/Denver",
          "Asia/Dhaka",
          "Asia/Dubai",
          "Europe/Dublin",
          "America/Edmonton",
          "Australia/Eucla",
          "Pacific/Fiji",
          "Pacific/Guam",
          "America/Halifax",
          "America/Havana",
          "Europe/Helsinki",
          "Asia/Ho_Chi_Minh",
          "Asia/Hong_Kong",
          "Pacific/Honolulu",
          "Asia/Kolkata",
          "Europe/Istanbul",
          "Asia/Jakarta",
          "Asia/Jerusalem",
          "Africa/Johannesburg",
          "Asia/Kabul",
          "Europe/Kaliningrad",
          "Asia/Karachi",
          "Asia/Kathmandu",
          "Pacific/Kiritimati",
          "Europe/Kyiv",
          "Africa/Lagos",
          "America/Lima",
          "Europe/Lisbon",
          "Europe/London",
          "Australia/Lord_Howe",
          "America/Los_Angeles",
          "Europe/Madrid",
          "Asia/Manila",
          "Pacific/Marquesas",
          "Australia/Melbourne",
          "America/Mexico_City",
          "Europe/Moscow",
          "Africa/Nairobi",
          "America/New_York",
          "America/St_Johns",
          "America/Nuuk",
          "Pacific/Pago_Pago",
          "Europe/Paris",
          "Australia/Perth",
          "America/Phoenix",
          "Atlantic/Reykjavik",
          "America/Regina",
          "Asia/Riyadh",
          "Europe/Rome",
          "America/Puerto_Rico",
          "America/Santiago",
          "America/Sao_Paulo",
          "Asia/Seoul",
          "Asia/Singapore",
          "Europe/Stockholm",
          "Australia/Sydney",
          "Pacific/Tahiti",
          "Asia/Taipei",
          "Asia/Tashkent",
          "Asia/Tehran",
          "America/Tijuana",
          "Asia/Tokyo",
          "Pacific/Tongatapu",
          "America/Toronto",
          "America/Vancouver",
          "Asia/Vladivostok",
          "Europe/Warsaw",
          "America/Whitehorse",
          "America/Winnipeg",
          "Asia/Yangon",
          "Asia/Yekaterinburg",
          "Europe/Zurich"
        ]
      },
      "zone3": {
        "title": "Time zone 3",
        "description": "Another time zone to meet with (IANA name), or None.",
        "type": "string",
        "enum": [
          "none",
          "UTC",
          "America/Adak",
          "Australia/Adelaide",
          "Asia/Almaty",
          "America/Anchorage",
          "Pacific/Apia",
          "Europe/Athens",
          "Pacific/Auckland",
          "Atlantic/Azores",
          "Asia/Baghdad",
          "Asia/Bangkok",
          "Asia/Shanghai",
          "Europe/Berlin",
          "America/Bogota",
          "Australia/Brisbane",
          "Europe/Brussels",
          "America/Argentina/Buenos_Aires",
          "Africa/Cairo",
          "America/Cancun",
          "Atlantic/Cape_Verde",
          "America/Caracas",
          "Africa/Casablanca",
          "Pacific/Chatham",
          "America/Chicago",
          "Asia/Colombo",
          "Australia/Darwin",
          "America/Denver",
          "Asia/Dhaka",
          "Asia/Dubai",
          "Europe/Dublin",
          "America/Edmonton",
          "Australia/Eucla",
          "Pacific/Fiji",
          "Pacific/Guam",
          "America/Halifax",
          "America/Havana",
          "Europe/Helsinki",
          "Asia/Ho_Chi_Minh",
          "Asia/Hong_Kong",
          "Pacific/Honolulu",
          "Asia/Kolkata",
          "Europe/Istanbul",
          "Asia/Jakarta",
          "Asia/Jerusalem",
          "Africa/Johannesburg",
          "Asia/Kabul",
          "Europe/Kaliningrad",
          "Asia/Karachi",
          "Asia/Kathmandu",
          "Pacific/Kiritimati",
          "Europe/Kyiv",
          "Africa/Lagos",
          "America/Lima",
          "Europe/Lisbon",
          "Europe/London",
          "Australia/Lord_Howe",
          "America/Los_Angeles",
          "Europe/Madrid",
          "Asia/Manila",
          "Pacific/Marquesas",
          "Australia/Melbourne",
          "America/Mexico_City",
          "Europe/Moscow",
          "Africa/Nairobi",
          "America/New_York",
          "America/St_Johns",
          "America/Nuuk",
          "Pacific/Pago_Pago",
          "Europe/Paris",
          "Australia/Perth",
          "America/Phoenix",
          "Atlantic/Reykjavik",
          "America/Regina",
          "Asia/Riyadh",
          "Europe/Rome",
          "America/Puerto_Rico",
          "America/Santiago",
          "America/Sao_Paulo",
          "Asia/Seoul",
          "Asia/Singapore",
          "Europe/Stockholm",
          "Australia/Sydney",
          "Pacific/Tahiti",
          "Asia/Taipei",
          "Asia/Tashkent",
          "Asia/Tehran",
          "America/Tijuana",
          "Asia/Tokyo",
          "Pacific/Tongatapu",
          "America/Toronto",
          "America/Vancouver",
          "Asia/Vladivostok",
          "Europe/Warsaw",
          "America/Whitehorse",
          "America/Winnipeg",
          "Asia/Yangon",
          "Asia/Yekaterinburg",
          "Europe/Zurich"
        ]
      },
      "zone4": {
        "title": "Time zone 4",
        "description": "Another time zone to meet with (IANA name), or None.",
        "type": "string",
        "enum": [
          "none",
          "UTC",
          "America/Adak",
          "Australia/Adelaide",
          "Asia/Almaty",
          "America/Anchorage",
          "Pacific/Apia",
          "Europe/Athens",
          "Pacific/Auckland",
          "Atlantic/Azores",
          "Asia/Baghdad",
          "Asia/Bangkok",
          "Asia/Shanghai",
          "Europe/Berlin",
          "America/Bogota",
          "Australia/Brisbane",
          "Europe/Brussels",
          "America/Argentina/Buenos_Aires",
          "Africa/Cairo",
          "America/Cancun",
          "Atlantic/Cape_Verde",
          "America/Caracas",
          "Africa/Casablanca",
          "Pacific/Chatham",
          "America/Chicago",
          "Asia/Colombo",
          "Australia/Darwin",
          "America/Denver",
          "Asia/Dhaka",
          "Asia/Dubai",
          "Europe/Dublin",
          "America/Edmonton",
          "Australia/Eucla",
          "Pacific/Fiji",
          "Pacific/Guam",
          "America/Halifax",
          "America/Havana",
          "Europe/Helsinki",
          "Asia/Ho_Chi_Minh",
          "Asia/Hong_Kong",
          "Pacific/Honolulu",
          "Asia/Kolkata",
          "Europe/Istanbul",
          "Asia/Jakarta",
          "Asia/Jerusalem",
          "Africa/Johannesburg",
          "Asia/Kabul",
          "Europe/Kaliningrad",
          "Asia/Karachi",
          "Asia/Kathmandu",
          "Pacific/Kiritimati",
          "Europe/Kyiv",
          "Africa/Lagos",
          "America/Lima",
          "Europe/Lisbon",
          "Europe/London",
          "Australia/Lord_Howe",
          "America/Los_Angeles",
          "Europe/Madrid",
          "Asia/Manila",
          "Pacific/Marquesas",
          "Australia/Melbourne",
          "America/Mexico_City",
          "Europe/Moscow",
          "Africa/Nairobi",
          "America/New_York",
          "America/St_Johns",
          "America/Nuuk",
          "Pacific/Pago_Pago",
          "Europe/Paris",
          "Australia/Perth",
          "America/Phoenix",
          "Atlantic/Reykjavik",
          "America/Regina",
          "Asia/Riyadh",
          "Europe/Rome",
          "America/Puerto_Rico",
          "America/Santiago",
          "America/Sao_Paulo",
          "Asia/Seoul",
          "Asia/Singapore",
          "Europe/Stockholm",
          "Australia/Sydney",
          "Pacific/Tahiti",
          "Asia/Taipei",
          "Asia/Tashkent",
          "Asia/Tehran",
          "America/Tijuana",
          "Asia/Tokyo",
          "Pacific/Tongatapu",
          "America/Toronto",
          "America/Vancouver",
          "Asia/Vladivostok",
          "Europe/Warsaw",
          "America/Whitehorse",
          "America/Winnipeg",
          "Asia/Yangon",
          "Asia/Yekaterinburg",
          "Europe/Zurich"
        ]
      },
      "zone5": {
        "title": "Time zone 5",
        "description": "Another time zone to meet with (IANA name), or None.",
        "type": "string",
        "enum": [
          "none",
          "UTC",
          "America/Adak",
          "Australia/Adelaide",
          "Asia/Almaty",
          "America/Anchorage",
          "Pacific/Apia",
          "Europe/Athens",
          "Pacific/Auckland",
          "Atlantic/Azores",
          "Asia/Baghdad",
          "Asia/Bangkok",
          "Asia/Shanghai",
          "Europe/Berlin",
          "America/Bogota",
          "Australia/Brisbane",
          "Europe/Brussels",
          "America/Argentina/Buenos_Aires",
          "Africa/Cairo",
          "America/Cancun",
          "Atlantic/Cape_Verde",
          "America/Caracas",
          "Africa/Casablanca",
          "Pacific/Chatham",
          "America/Chicago",
          "Asia/Colombo",
          "Australia/Darwin",
          "America/Denver",
          "Asia/Dhaka",
          "Asia/Dubai",
          "Europe/Dublin",
          "America/Edmonton",
          "Australia/Eucla",
          "Pacific/Fiji",
          "Pacific/Guam",
          "America/Halifax",
          "America/Havana",
          "Europe/Helsinki",
          "Asia/Ho_Chi_Minh",
          "Asia/Hong_Kong",
          "Pacific/Honolulu",
          "Asia/Kolkata",
          "Europe/Istanbul",
          "Asia/Jakarta",
          "Asia/Jerusalem",
          "Africa/Johannesburg",
          "Asia/Kabul",
          "Europe/Kaliningrad",
          "Asia/Karachi",
          "Asia/Kathmandu",
          "Pacific/Kiritimati",
          "Europe/Kyiv",
          "Africa/Lagos",
          "America/Lima",
          "Europe/Lisbon",
          "Europe/London",
          "Australia/Lord_Howe",
          "America/Los_Angeles",
          "Europe/Madrid",
          "Asia/Manila",
          "Pacific/Marquesas",
          "Australia/Melbourne",
          "America/Mexico_City",
          "Europe/Moscow",
          "Africa/Nairobi",
          "America/New_York",
          "America/St_Johns",
          "America/Nuuk",
          "Pacific/Pago_Pago",
          "Europe/Paris",
          "Australia/Perth",
          "America/Phoenix",
          "Atlantic/Reykjavik",
          "America/Regina",
          "Asia/Riyadh",
          "Europe/Rome",
          "America/Puerto_Rico",
          "America/Santiago",
          "America/Sao_Paulo",
          "Asia/Seoul",
          "Asia/Singapore",
          "Europe/Stockholm",
          "Australia/Sydney",
          "Pacific/Tahiti",
          "Asia/Taipei",
          "Asia/Tashkent",
          "Asia/Tehran",
          "America/Tijuana",
          "Asia/Tokyo",
          "Pacific/Tongatapu",
          "America/Toronto",
          "America/Vancouver",
          "Asia/Vladivostok",
          "Europe/Warsaw",
          "America/Whitehorse",
          "America/Winnipeg",
          "Asia/Yangon",
          "Asia/Yekaterinburg",
          "Europe/Zurich"
        ]
      },
      "on": {
        "title": "Date",
        "description": "The date of the meeting in your time zone. Today, unless you change it.",
        "type": "string",
        "format": "date"
      },
      "start": {
        "title": "Working hours start",
        "description": "When the working day starts, on the local clock of every zone.",
        "type": "string",
        "pattern": "^\\d{2}:\\d{2}(:\\d{2})?$"
      },
      "end": {
        "title": "Working hours end",
        "description": "When the working day ends, on the local clock of every zone; later than the start.",
        "type": "string",
        "pattern": "^\\d{2}:\\d{2}(:\\d{2})?$"
      }
    }
  },
  "outputs": {
    "overlap": {
      "label": "Overlap",
      "description": "How long the working hours of every chosen zone overlap on the date.",
      "format": "text"
    },
    "local1": {
      "label": "Your time zone",
      "description": "The overlap on your clock.",
      "format": "text"
    },
    "local2": {
      "label": "Time zone 2",
      "description": "The overlap on the clock of time zone 2.",
      "format": "text"
    },
    "local3": {
      "label": "Time zone 3",
      "description": "The overlap on the clock of time zone 3.",
      "format": "text"
    },
    "local4": {
      "label": "Time zone 4",
      "description": "The overlap on the clock of time zone 4.",
      "format": "text"
    },
    "local5": {
      "label": "Time zone 5",
      "description": "The overlap on the clock of time zone 5.",
      "format": "text"
    },
    "none": {
      "label": "No overlap",
      "description": "Shown when no time is within the working hours in every zone.",
      "format": "text"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "zone1": "America/New_York",
      "zone2": "Europe/London",
      "zone3": "Europe/Berlin",
      "zone4": "none",
      "zone5": "none",
      "on": "2026-10-19",
      "start": "09:00",
      "end": "17:00"
    },
    "outputs": {
      "overlap": "2 hours",
      "local1": "New York (US Eastern): Mon, Oct 19, 9:00 AM to 11:00 AM",
      "local2": "London, UK: Mon, Oct 19, 2:00 PM to 4:00 PM",
      "local3": "Berlin, Germany: Mon, Oct 19, 3:00 PM to 5:00 PM"
    },
    "text": "On October 19, 2026, working hours of 9:00 AM to 5:00 PM overlap for 2 hours in every chosen time zone."
  },
  "examples": [
    {
      "given": {
        "zone1": "America/New_York",
        "zone2": "Europe/London",
        "zone3": "Europe/Berlin",
        "zone4": "none",
        "zone5": "none",
        "on": "2026-10-19",
        "start": "09:00",
        "end": "17:00"
      },
      "expect": {
        "overlap": "2 hours",
        "local1": "New York (US Eastern): Mon, Oct 19, 9:00 AM to 11:00 AM",
        "local2": "London, UK: Mon, Oct 19, 2:00 PM to 4:00 PM",
        "local3": "Berlin, Germany: Mon, Oct 19, 3:00 PM to 5:00 PM"
      },
      "source": "IANA Time Zone Database, tzdata 2026a (https://www.iana.org/time-zones); Python 3 zoneinfo with tzdata 2026a, from the rules in content.mdx (docs/progress/WP-141/truth_tz.py)"
    },
    {
      "given": {
        "zone1": "America/New_York",
        "zone2": "Asia/Kolkata",
        "zone3": "none",
        "zone4": "none",
        "zone5": "none",
        "on": "2026-10-19",
        "start": "09:00",
        "end": "17:00"
      },
      "expect": {
        "overlap": "0 minutes",
        "none": "No time on Monday, October 19, 2026 is between 9:00 AM and 5:00 PM in every zone. Try longer working hours or fewer zones."
      },
      "source": "IANA Time Zone Database, tzdata 2026a (https://www.iana.org/time-zones); Python 3 zoneinfo with tzdata 2026a, from the rules in content.mdx (docs/progress/WP-141/truth_tz.py)"
    },
    {
      "given": {
        "zone1": "America/New_York",
        "zone2": "Asia/Kolkata",
        "zone3": "none",
        "zone4": "none",
        "zone5": "none",
        "on": "2026-10-19",
        "start": "08:00",
        "end": "20:00"
      },
      "expect": {
        "overlap": "2 hours 30 minutes",
        "local1": "New York (US Eastern): Mon, Oct 19, 8:00 AM to 10:30 AM",
        "local2": "India (New Delhi, Mumbai, Kolkata): Mon, Oct 19, 5:30 PM to 8:00 PM"
      },
      "source": "IANA Time Zone Database, tzdata 2026a (https://www.iana.org/time-zones); Python 3 zoneinfo with tzdata 2026a, from the rules in content.mdx (docs/progress/WP-141/truth_tz.py)"
    },
    {
      "given": {
        "zone1": "America/Chicago",
        "zone2": "America/New_York",
        "zone3": "Europe/London",
        "zone4": "Europe/Paris",
        "zone5": "Africa/Lagos",
        "on": "2026-10-19",
        "start": "09:00",
        "end": "17:00"
      },
      "expect": {
        "overlap": "1 hour",
        "local1": "Chicago (US Central): Mon, Oct 19, 9:00 AM to 10:00 AM",
        "local2": "New York (US Eastern): Mon, Oct 19, 10:00 AM to 11:00 AM",
        "local3": "London, UK: Mon, Oct 19, 3:00 PM to 4:00 PM",
        "local4": "Paris, France: Mon, Oct 19, 4:00 PM to 5:00 PM",
        "local5": "Lagos, Nigeria: Mon, Oct 19, 3:00 PM to 4:00 PM"
      },
      "source": "IANA Time Zone Database, tzdata 2026a (https://www.iana.org/time-zones); Python 3 zoneinfo with tzdata 2026a, from the rules in content.mdx (docs/progress/WP-141/truth_tz.py)"
    },
    {
      "given": {
        "zone1": "America/Los_Angeles",
        "zone2": "Australia/Sydney",
        "zone3": "none",
        "zone4": "none",
        "zone5": "none",
        "on": "2026-10-19",
        "start": "09:00",
        "end": "17:00"
      },
      "expect": {
        "overlap": "2 hours",
        "local1": "Los Angeles (US Pacific): Mon, Oct 19, 3:00 PM to 5:00 PM",
        "local2": "Sydney, Australia: Tue, Oct 20, 9:00 AM to 11:00 AM"
      },
      "source": "IANA Time Zone Database, tzdata 2026a (https://www.iana.org/time-zones); Python 3 zoneinfo with tzdata 2026a, from the rules in content.mdx (docs/progress/WP-141/truth_tz.py)"
    },
    {
      "given": {
        "zone1": "America/New_York",
        "zone2": "America/Toronto",
        "zone3": "none",
        "zone4": "none",
        "zone5": "none",
        "on": "2026-03-08",
        "start": "02:30",
        "end": "04:00"
      },
      "expect": {
        "overlap": "1 hour",
        "local1": "New York (US Eastern): Sun, Mar 8, 3:00 AM to 4:00 AM",
        "local2": "Toronto, Canada: Sun, Mar 8, 3:00 AM to 4:00 AM"
      },
      "source": "IANA Time Zone Database, tzdata 2026a (https://www.iana.org/time-zones); Python 3 zoneinfo with tzdata 2026a, from the rules in content.mdx (docs/progress/WP-141/truth_tz.py)"
    },
    {
      "given": {
        "zone1": "America/New_York",
        "zone2": "America/Toronto",
        "zone3": "none",
        "zone4": "none",
        "zone5": "none",
        "on": "2026-11-01",
        "start": "01:00",
        "end": "02:00"
      },
      "expect": {
        "overlap": "2 hours",
        "local1": "New York (US Eastern): Sun, Nov 1, 1:00 AM to 2:00 AM",
        "local2": "Toronto, Canada: Sun, Nov 1, 1:00 AM to 2:00 AM"
      },
      "source": "IANA Time Zone Database, tzdata 2026a (https://www.iana.org/time-zones); Python 3 zoneinfo with tzdata 2026a, from the rules in content.mdx (docs/progress/WP-141/truth_tz.py)"
    },
    {
      "given": {
        "zone1": "Pacific/Auckland",
        "zone2": "America/Los_Angeles",
        "zone3": "none",
        "zone4": "none",
        "zone5": "none",
        "on": "2026-10-20",
        "start": "00:00",
        "end": "23:30"
      },
      "expect": {
        "overlap": "23 hours",
        "local1": "Auckland, New Zealand: Tue, Oct 20, 12:00 AM to 7:30 PM; Tue, Oct 20, 8:00 PM to 11:30 PM",
        "local2": "Los Angeles (US Pacific): Mon, Oct 19, 4:00 AM to 11:30 PM; Tue, Oct 20, 12:00 AM to 3:30 AM"
      },
      "source": "IANA Time Zone Database, tzdata 2026a (https://www.iana.org/time-zones); Python 3 zoneinfo with tzdata 2026a, from the rules in content.mdx (docs/progress/WP-141/truth_tz.py)"
    }
  ],
  "sources": [
    "IANA Time Zone Database, tzdata 2026a: the zones and their daylight saving rules. https://www.iana.org/time-zones",
    "15 U.S.C. 260a, advancement of time: US daylight saving time from the second Sunday in March to the first Sunday in November. https://www.law.cornell.edu/uscode/text/15/260a"
  ],
  "related": [
    "time-zone-converter",
    "forex-market-hours",
    "time-zones",
    "us-time-zones"
  ],
  "changelog": []
}