{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"world-clock"},"result":{"entity_type":"calculator","id":"world-clock","calculator_id":"world-clock","canonical_url":"https://tttkmbb.com/time/world-clock","name":"World Clock Calculator","title":"World Clock – Local Time in Several Cities for One Reference Date and Time","category":"time","category_name":"Time & Geography","tool_name":"calculate_world_clock","featured_mcp_tool":false,"description":"Takes a reference date and time in one IANA time zone and lists the corresponding local date, time, weekday and UTC offset in each zone of a list, using the tz database rules built into ICU (daylight saving included).","use_when":"You are scheduling across several cities and need the local time in each of them for one instant, or want to see the spread of UTC offsets.","do_not_use_when":"You only convert between two zones (use time-zone-converter) or need an epoch value (use unix-timestamp).","inputs":[{"name":"date","label":"Reference date","type":"date","required":false,"default":"today","description":"Calendar date of the reference time in the reference zone; defaults to the current UTC date.","example":"2026-09-23"},{"name":"time","label":"Reference time","type":"string","required":false,"default":"12:00","description":"Wall-clock time in the reference zone, 24-hour HH:MM.","example":"09:00"},{"name":"zone","label":"Reference time zone","type":"string","required":false,"default":"UTC","description":"IANA time zone in which date and time are given.","example":"Australia/Adelaide"},{"name":"zones","label":"Zones to show","type":"string_list","required":true,"description":"List of IANA time zones to display (comma-separated or JSON array), e.g. America/New_York, Europe/London, Asia/Tokyo.","example":["America/New_York","Europe/London","Asia/Tokyo"]}],"outputs":[{"name":"utc_datetime","label":"UTC","type":"string","decimals":4,"description":"The reference instant in UTC (ISO 8601)."},{"name":"reference_datetime","label":"Reference date-time","type":"string","decimals":4,"description":"The reference time with its UTC offset (ISO 8601)."},{"name":"clocks","label":"Local times","type":"list","decimals":4,"description":"One entry per zone: zone, local_date, local_time, weekday, utc_offset, abbreviation and day_offset (local date minus reference date, in days)."},{"name":"offset_span_hours","label":"Offset span","type":"number","unit":"h","decimals":2,"description":"Largest minus smallest UTC offset among the reference zone and all listed zones."}],"input_schema":{"type":"object","properties":{"date":{"description":"Calendar date of the reference time in the reference zone; defaults to the current UTC date.","type":"string","format":"date","default":"today","examples":["2026-09-23"]},"time":{"description":"Wall-clock time in the reference zone, 24-hour HH:MM.","type":"string","default":"12:00","examples":["09:00"]},"zone":{"description":"IANA time zone in which date and time are given.","type":"string","default":"UTC","examples":["Australia/Adelaide"]},"zones":{"description":"List of IANA time zones to display (comma-separated or JSON array), e.g. America/New_York, Europe/London, Asia/Tokyo.","type":"array","items":{"type":"string"},"examples":[["America/New_York","Europe/London","Asia/Tokyo"]]}},"additionalProperties":false,"required":["zones"]},"output_schema":{"type":"object","properties":{"utc_datetime":{"description":"The reference instant in UTC (ISO 8601).","type":"string"},"reference_datetime":{"description":"The reference time with its UTC offset (ISO 8601).","type":"string"},"clocks":{"description":"One entry per zone: zone, local_date, local_time, weekday, utc_offset, abbreviation and day_offset (local date minus reference date, in days).","type":"array"},"offset_span_hours":{"description":"Largest minus smallest UTC offset among the reference zone and all listed zones. Unit: h.","type":"number","x-unit":"h"}}},"formula":"utc = reference wall time − offset_reference; for each zone: local = utc + offset_zone(utc); day_offset = local_date − reference_date","method":"Offsets come from the IANA tz database via Intl.DateTimeFormat. Non-existent reference times (clocks jumped forward) are moved forward by the gap; ambiguous ones take their first occurrence.","sources":[{"name":"IANA Time Zone Database (tz)","url":"https://www.iana.org/time-zones","type":"standard","retrieved_at":"2026-09-24"},{"name":"List of tz database time zones (Wikipedia)","url":"https://en.wikipedia.org/wiki/List_of_tz_database_time_zones","type":"reference","retrieved_at":"2026-09-24"}],"freshness":{"type":"daily","max_age_seconds":86400,"note":"Depends on the current date unless the date is supplied."},"examples":[{"name":"09:00 Adelaide on 2026-09-23 in New York, London, Tokyo","inputs":{"date":"2026-09-23","time":"09:00","zone":"Australia/Adelaide","zones":["America/New_York","Europe/London","Asia/Tokyo"]},"expected":{"utc_datetime":"2026-09-22T23:30:00Z","clocks":[{"zone":"America/New_York","local_date":"2026-09-22","local_time":"19:30","utc_offset":"-04:00","day_offset":-1},{"zone":"Europe/London","local_date":"2026-09-23","local_time":"00:30","utc_offset":"+01:00","day_offset":0},{"zone":"Asia/Tokyo","local_date":"2026-09-23","local_time":"08:30","utc_offset":"+09:00","day_offset":0}],"offset_span_hours":13.5},"url":"https://tttkmbb.com/api/v1/calculate/world-clock?date=2026-09-23&time=09%3A00&zone=Australia%2FAdelaide&zones=America%2FNew_York%2CEurope%2FLondon%2CAsia%2FTokyo"},{"name":"New Year 2026 00:00 UTC in Auckland, Kolkata, Los Angeles","inputs":{"date":"2026-01-01","time":"00:00","zone":"UTC","zones":["Pacific/Auckland","Asia/Kolkata","America/Los_Angeles"]},"expected":{"clocks":[{"zone":"Pacific/Auckland","local_date":"2026-01-01","local_time":"13:00","utc_offset":"+13:00"},{"zone":"Asia/Kolkata","local_time":"05:30","utc_offset":"+05:30"},{"zone":"America/Los_Angeles","local_date":"2025-12-31","local_time":"16:00","utc_offset":"-08:00","day_offset":-1}],"offset_span_hours":21},"url":"https://tttkmbb.com/api/v1/calculate/world-clock?date=2026-01-01&time=00%3A00&zone=UTC&zones=Pacific%2FAuckland%2CAsia%2FKolkata%2CAmerica%2FLos_Angeles"}],"faq":[{"q":"Why does a city show a different date?","a":"day_offset is the local calendar date minus the reference date: −1 means the instant falls on the previous day there, +1 on the next day (e.g. Auckland is ahead of Los Angeles by up to 21 hours)."},{"q":"Can I use city names instead of zone names?","a":"No; use the IANA zone of the city (Paris → Europe/Paris, Mumbai → Asia/Kolkata, Sydney → Australia/Sydney). Invalid names return an INVALID_PARAMETER error."}],"tags":["world clock","time in cities","meeting planner","time zones","utc offset list"],"related":[{"calculator_id":"time-zone-converter","reason":"Two-zone conversion with day difference and abbreviations."},{"calculator_id":"unix-timestamp","reason":"Epoch seconds for the same instant."}],"links":{"html":"https://tttkmbb.com/time/world-clock","markdown":"https://tttkmbb.com/time/world-clock.md","json":"https://tttkmbb.com/time/world-clock.json","api":"https://tttkmbb.com/api/v1/calculate/world-clock","schema":"https://tttkmbb.com/api/v1/calculators/world-clock","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T01:51:38Z"}