odyssey4me/google-calendar

Create, update, and organize Google Calendar events and schedules. Check availability, book time, and manage calendars. Use when asked to schedule a meeting, set up an appointment, book a call, check gcal, or manage calendar events.

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Google Calendar Timezone Guide

Name: odyssey4me/google-calendar
Rating: 0.94 (1 reviews)
Author: odyssey4me

This guide explains how to work with dates, times, and timezones in Google Calendar.

Time Format Overview

Google Calendar uses RFC3339 format for timestamps, which is an internet standard for representing dates and times.

RFC3339 Format

YYYY-MM-DDTHH:MM:SS±HH:MM

Components:

YYYY-MM-DD - Date (year-month-day)
T - Separator between date and time
HH:MM:SS - Time (hours:minutes:seconds)
±HH:MM - Timezone offset from UTC, OR Z for UTC

Examples

UTC Time

Use Z suffix to indicate UTC (Coordinated Universal Time):

2026-01-24T10:00:00Z       # 10:00 AM UTC
2026-01-24T15:30:00Z       # 3:30 PM UTC
2026-12-31T23:59:59Z       # December 31, 11:59:59 PM UTC

Time with Timezone Offset

Specify explicit timezone offset:

# Eastern Standard Time (EST = UTC-5)
2026-01-24T10:00:00-05:00

# Eastern Daylight Time (EDT = UTC-4)
2026-06-24T10:00:00-04:00

# Pacific Standard Time (PST = UTC-8)
2026-01-24T10:00:00-08:00

# Central European Time (CET = UTC+1)
2026-01-24T10:00:00+01:00

# India Standard Time (IST = UTC+5:30)
2026-01-24T10:00:00+05:30

All-Day Events

Use date format (YYYY-MM-DD) without time:

2026-01-24      # All day on January 24, 2026
2026-12-25      # All day on December 25, 2026

For all-day events, optionally specify timezone using --timezone:

python scripts/google-calendar.py events create \
  --summary "Conference" \
  --start "2026-01-24" \
  --end "2026-01-25" \
  --timezone "America/New_York"

Common Timezone Offsets

North America

Timezone	Standard (Winter)	Daylight (Summer)
Eastern (ET)	UTC-5	UTC-4
Central (CT)	UTC-6	UTC-5
Mountain (MT)	UTC-7	UTC-6
Pacific (PT)	UTC-8	UTC-7
Alaska (AKT)	UTC-9	UTC-8
Hawaii (HST)	UTC-10	No DST

Europe

Timezone	Standard (Winter)	Daylight (Summer)
GMT/WET	UTC+0	UTC+1
CET	UTC+1	UTC+2
EET	UTC+2	UTC+3

Asia Pacific

Timezone	Offset
India (IST)	UTC+5:30
China (CST)	UTC+8
Japan (JST)	UTC+9
Australia Eastern	UTC+10 / UTC+11 (DST)
New Zealand	UTC+12 / UTC+13 (DST)

IANA Timezone Names

For all-day events, you can use IANA timezone database names with the --timezone flag:

America/New_York
America/Los_Angeles
America/Chicago
America/Denver
Europe/London
Europe/Paris
Europe/Berlin
Asia/Tokyo
Asia/Shanghai
Asia/Kolkata
Australia/Sydney
Pacific/Auckland

Example:

python scripts/google-calendar.py events create \
  --summary "All Day Event" \
  --start "2026-01-24" \
  --end "2026-01-25" \
  --timezone "America/New_York"

Daylight Saving Time (DST)

When working with timezones, be aware of Daylight Saving Time transitions:

Spring forward: Clocks move ahead (e.g., EST UTC-5 becomes EDT UTC-4)
Fall back: Clocks move back (e.g., EDT UTC-4 becomes EST UTC-5)

DST Transitions in 2026 (US)

March 8, 2026: Clocks spring forward at 2:00 AM
November 1, 2026: Clocks fall back at 2:00 AM

Tip: Use UTC timestamps (with Z suffix) to avoid DST complications, or use explicit timezone offsets that match the current DST status.

Best Practices

1. Use UTC for Consistency

When possible, use UTC timestamps to avoid timezone confusion:

python scripts/google-calendar.py events create \
  --summary "Meeting" \
  --start "2026-01-24T15:00:00Z" \
  --end "2026-01-24T16:00:00Z"

2. Be Explicit with Offsets

If using local time, always include the timezone offset:

# Good - explicit offset
--start "2026-01-24T10:00:00-05:00"

# Avoid - ambiguous without timezone
--start "2026-01-24T10:00:00"

3. Consider Attendees' Timezones

When scheduling meetings with attendees in different timezones, Google Calendar automatically adjusts display times for each attendee based on their calendar settings.

Example: An event at 2026-01-24T15:00:00Z (3 PM UTC) will display as:

10 AM EST (UTC-5)
11 PM CST (UTC+8) in China
2 AM JST (UTC+9) in Japan (next day!)

4. All-Day Events and Timezones

For all-day events, specifying timezone ensures the event appears on the correct calendar day for that timezone:

# Without timezone - may shift to adjacent day in some timezones
python scripts/google-calendar.py events create \
  --summary "Holiday" \
  --start "2026-12-25" \
  --end "2026-12-26"

# With timezone - ensures correct day
python scripts/google-calendar.py events create \
  --summary "Holiday" \
  --start "2026-12-25" \
  --end "2026-12-26" \
  --timezone "America/New_York"

Converting Between Timezones

Manual Conversion

To convert from one timezone to another:

Convert local time to UTC
Apply target timezone offset

Example: Convert 2 PM EST to Tokyo time

2 PM EST = 14:00-05:00 (EST is UTC-5)
In UTC  = 14:00 + 05:00 = 19:00 UTC
In JST  = 19:00 + 09:00 = 04:00 JST next day (JST is UTC+9)

Result: 2026-01-24T14:00:00-05:00 (EST) = 2026-01-25T04:00:00+09:00 (JST)

Using Date Command (Linux/macOS)

# Convert EST to UTC
date -u -d "2026-01-24T14:00:00-05:00"

# Convert UTC to local timezone
date -d "2026-01-24T19:00:00Z"

Python Helper

from datetime import datetime, timezone

# Parse RFC3339 timestamp
dt = datetime.fromisoformat("2026-01-24T14:00:00-05:00")

# Convert to UTC
utc_dt = dt.astimezone(timezone.utc)
print(utc_dt.isoformat())  # 2026-01-24T19:00:00+00:00

Command Examples

Create event in specific timezone

# 10 AM Eastern Time on January 24
python scripts/google-calendar.py events create \
  --summary "Team Meeting" \
  --start "2026-01-24T10:00:00-05:00" \
  --end "2026-01-24T11:00:00-05:00"

List events in time range (UTC)

python scripts/google-calendar.py events list \
  --time-min "2026-01-24T00:00:00Z" \
  --time-max "2026-01-31T23:59:59Z"

Create all-day event with timezone

python scripts/google-calendar.py events create \
  --summary "Company Offsite" \
  --start "2026-01-24" \
  --end "2026-01-26" \
  --timezone "America/Los_Angeles"

Check availability across timezones

# Check 9 AM - 5 PM EST (14:00 - 22:00 UTC)
python scripts/google-calendar.py freebusy \
  --start "2026-01-24T14:00:00Z" \
  --end "2026-01-24T22:00:00Z" \
  --calendars "primary,colleague@example.com"

Google Calendar API Timezone Behavior

Event Display

Google Calendar stores events in UTC internally
Events are displayed in each user's local timezone
All-day events respect the timezone they were created in
Recurring events handle DST transitions automatically

Timezone Information in API Responses

When you retrieve an event, Google Calendar provides:

{
  "start": {
    "dateTime": "2026-01-24T10:00:00-05:00",
    "timeZone": "America/New_York"
  },
  "end": {
    "dateTime": "2026-01-24T11:00:00-05:00",
    "timeZone": "America/New_York"
  }
}

Or for all-day events:

{
  "start": {
    "date": "2026-01-24"
  },
  "end": {
    "date": "2026-01-25"
  }
}

Common Issues and Solutions

Issue: Event appears on wrong day

Cause: Timezone offset caused date boundary crossing

Solution: Use explicit timezone or UTC timestamps

# Wrong - might appear on wrong day
--start "2026-01-24T23:00:00-08:00"  # 11 PM PST = 7 AM UTC next day

# Better - explicitly in UTC
--start "2026-01-25T07:00:00Z"

Issue: Recurring events shift with DST

Cause: Fixed offset doesn't account for DST transitions

Solution: Use IANA timezone names for recurring events (requires direct API access, not available via command line for this skill)

Issue: Meeting time confusion across timezones

Cause: Participants in different timezones see different local times

Solution: Include timezone in event description or use UTC:

python scripts/google-calendar.py events create \
  --summary "Global Team Call" \
  --start "2026-01-24T15:00:00Z" \
  --end "2026-01-24T16:00:00Z" \
  --description "3 PM UTC / 10 AM EST / 7 AM PST / 11 PM CST (China)"

Additional Resources

Install with Tessl CLI

npx tessl i odyssey4me/google-calendar@0.3.1

references

calendar-timezones.md

scripts