- name
- timezone-helper
- description
- Time zone conversion, world clock, and meeting planner. Use when the user asks about current time in a city, needs to convert time between zones, wants to schedule a meeting across multiple time zones, or asks about daylight saving time (DST). Built-in IANA timezone data for 200+ cities. No API key, no scripts, no Python required — fully offline.
- version
- 1.0.0
- license
- MIT-0
- metadata
- openclaw
- emoji
- 🌍
Timezone Helper
Convert times between any time zones, plan global meetings, check DST status. Zero dependencies — all data built-in, works in any environment.
Full city-to-timezone mapping: see references/cities.md.
When to use
- "What time is it in Tokyo right now?"
- "Convert 3pm New York to London time"
- "Schedule a meeting for our team in SF, London and Singapore"
- "Does Germany observe DST? When does it change?"
- "What's the UTC offset for IST?"
- "Find a time that works for NYC, Berlin and Beijing"
Core concepts
UTC offset
Every timezone is expressed as UTC±HH:MM.
- UTC+9 = 9 hours ahead of UTC (Tokyo, Seoul)
- UTC-5 = 5 hours behind UTC (New York EST, Lima)
- UTC+0 = same as UTC (London GMT, Reykjavik)
DST (Daylight Saving Time)
Some regions shift clocks ±1 hour seasonally:
- Northern Hemisphere (US, Europe, etc.): spring forward, fall back
- US: second Sunday March → first Sunday November - EU: last Sunday March → last Sunday October
- Southern Hemisphere (Australia, NZ, etc.): opposite — DST in Oct–Apr
- No DST: China, Japan, India, most of Africa, Middle East, Southeast Asia
Always confirm the current date when doing DST-sensitive conversions.
Step 1: Resolve city/region to IANA timezone
Use the table in references/cities.md to map user input to an IANA zone. Common shortcuts to recognize:
EST / ET → America/New_York (UTC-5 standard, UTC-4 DST)
CST (US) → America/Chicago (UTC-6 standard, UTC-5 DST)
MST → America/Denver (UTC-7 standard, UTC-6 DST)
PST / PT → America/Los_Angeles (UTC-8 standard, UTC-7 DST)
GMT / UTC → UTC (UTC+0, no DST)
BST → Europe/London (UTC+1, summer only)
CET / CEST → Europe/Paris (UTC+1 standard, UTC+2 DST)
IST → Asia/Kolkata (UTC+5:30, no DST)
CST (China) → Asia/Shanghai (UTC+8, no DST)
JST → Asia/Tokyo (UTC+9, no DST)
AEST / AEDT → Australia/Sydney (UTC+10 standard, UTC+11 DST)Step 2: Apply UTC offset
Conversion formula:
Target time = Source time + (Target UTC offset) - (Source UTC offset)If result crosses midnight: adjust date ±1 day accordingly.
Example:
Convert 14:00 New York (EST, UTC-5) → Tokyo (JST, UTC+9)
Difference = +9 - (-5) = +14 hours
14:00 + 14h = 28:00 → 04:00 next day TokyoStep 3: Check DST status
Before finalizing, verify whether DST is currently active for each zone. If the user's current date is near a DST transition, note the change.
DST transitions (approximate):
US (spring forward): Second Sunday of March, 02:00 → 03:00
US (fall back): First Sunday of November, 02:00 → 01:00
EU (spring forward): Last Sunday of March, 01:00 UTC → 02:00 UTC
EU (fall back): Last Sunday of October, 01:00 UTC → 00:00 UTC
Australia/Sydney: First Sunday of October, 02:00 → 03:00
Australia/Sydney: First Sunday of April, 03:00 → 02:00Output formats
Single conversion
🌍 Time Zone Conversion
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Source: 3:00 PM Wed, Mar 20 — New York (EST, UTC-5)
Target: 8:00 PM Wed, Mar 20 — London (GMT, UTC+0)
4:00 AM Thu, Mar 21 — Tokyo (JST, UTC+9)
1:00 AM Thu, Mar 21 — Singapore (SGT, UTC+8)World clock (current time)
🕐 Current World Time (based on: 15:00 UTC)
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🇺🇸 New York 10:00 AM Wed (EST, UTC-5)
🇬🇧 London 15:00 Wed (GMT, UTC+0)
🇩🇪 Berlin 16:00 Wed (CET, UTC+1)
🇮🇳 Mumbai 20:30 Wed (IST, UTC+5:30)
🇨🇳 Beijing 23:00 Wed (CST, UTC+8)
🇯🇵 Tokyo 00:00 Thu (JST, UTC+9)
🇦🇺 Sydney 02:00 Thu (AEDT, UTC+11)Meeting planner
📅 Meeting Planner
━━━━━━━━━━━━━━━━━━━━
Participants: San Francisco / London / Singapore
Option A — Best for SF + London:
San Francisco 09:00 AM (PST, UTC-8) ✅ work hours
London 17:00 (GMT, UTC+0) ✅ end of day
Singapore 01:00 AM (SGT, UTC+8) ❌ midnight
Option B — Best for London + Singapore:
San Francisco 01:00 AM (PST, UTC-8) ❌ midnight
London 09:00 (GMT, UTC+0) ✅ work hours
Singapore 17:00 (SGT, UTC+8) ✅ work hours
No perfect overlap exists. Recommended compromise:
San Francisco 06:00 AM ⚠️ early
London 14:00 ✅
Singapore 22:00 ⚠️ late eveningDST query
🕐 DST Information: Germany (Europe/Berlin)
━━━━━━━━━━━━━━━━━━━━
Current offset: UTC+1 (CET — Central European Time)
DST observed: Yes
DST offset: UTC+2 (CEST — Central European Summer Time)
Spring forward: Last Sunday of March → clocks +1h at 02:00
Fall back: Last Sunday of October → clocks -1h at 03:00
2026 transitions: Mar 29 (→ CEST) / Oct 25 (→ CET)Meeting planner logic
When finding meeting overlap across zones:
1. Define "work hours" as 09:00–18:00 local time
2. Define "acceptable" as 07:00–21:00 local time
3. Convert each hour of the day to all participants' local times
4. Score each UTC hour:
- All in work hours → ✅ ideal
- All in acceptable → ⚠️ workable
- Any outside 07-21 → ❌ avoid
5. Present top 2-3 options with clear local times
6. If no ideal slot exists, say so explicitly and suggest best compromiseNotes
- Always ask for or confirm the current date when DST status matters
- "IST" is ambiguous: could be India (UTC+5:30), Israel (UTC+2), or Ireland (UTC+0/+1) — clarify with user if context is unclear
- "CST" is ambiguous: US Central (UTC-6/-5) or China Standard (UTC+8) — resolve from context
- Half-hour and 45-minute offsets exist: India (UTC+5:30), Iran (UTC+3:30), Nepal (UTC+5:45), Australia/Lord Howe (UTC+10:30/+11)
- For precise current-time queries, note that this skill provides static offset data; the actual current time depends on the system clock