CalcaTools

Time Zone Converter

A free tool to convert time between major world time zones. Essential for remote teams, international meetings, and global business scheduling.

Last updated: June 2026 · Free · No sign-up required

Quick reference

12:00 New York (EDT)Equals
London17:00
Dubai20:00
Delhi21:30
Singapore00:00 (+1 day)
Sydney02:00 (+1 day)

Interpretation guide

Meeting windowCoverage
13:00–16:00 UTCUS East morning + Europe afternoon
06:00–08:00 UTCEurope morning + Asia afternoon
22:00–00:00 UTCUS West afternoon + Asia-Pacific morning

Formula & methodology

Formula: Target time = source time − source UTC offset + target UTC offset (DST applied per zone rules)

  1. Pick the source city/zone and a date-time.
  2. The converter applies each zone’s current UTC offset — including daylight-saving rules for that specific date.
  3. All selected cities display the local equivalent, flagging day changes.

Worked example: 12:00 in New York (summer, EDT = UTC−4) is 17:00 London, 21:30 Delhi and 02:00 next-day Sydney — note India’s half-hour offset and the date line’s +1 day.

Frequently asked questions

How do I convert time between zones manually?
Go through UTC: subtract the source offset, add the target’s. 12:00 EDT (UTC−4) → 16:00 UTC → 21:30 IST (UTC+5:30). The converter does this with the correct DST offsets for your chosen date.
Why do conversions change twice a year?
Daylight saving — the US shifts in March/November, Europe in March/October, on different weekends. For a few weeks the NY–London gap is 4 hours instead of 5; date-aware conversion handles it.
Which zones have half-hour offsets?
India (+5:30), Iran (+3:30), Afghanistan (+4:30), Myanmar (+6:30), parts of Australia (+9:30) — and Nepal’s quarter-hour +5:45. Always convert by zone, not by "hours difference" memory.
How do I find a meeting time for 3 continents?
Anchor on UTC: 13:00–16:00 UTC catches US East morning and Europe afternoon; adding Asia pushes toward 12:00–13:00 UTC with someone’s evening. The comparison view shows the pain evenly.
Whats the difference between GMT and UTC?
For practical purposes none — UTC is the modern atomic-time standard, GMT the historical solar term. "GMT+5:30"-style offsets mean the same thing as UTC offsets.

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