Timezone

🕐 Timezone Converter

Convert any date & time between 100+ world timezones with automatic DST support.

📅 Date & Time

🌍 From Timezone

🎯 Convert To

Tap to select timezones... ▼

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🌐 World Clock — Live

⚡ Quick Timezone Conversions

⏱ Time Difference Calculator

Timezone A

Timezone B

📅 Meeting Planner — Business Hours Overlap

Shows each World Clock city's standard 9 AM–5 PM working hours on a 24-hour UTC grid. █ = working hours · █ = current hour (outlined).

🗺️ Current Time Zones — Visual Map

Each column is one UTC offset (UTC−12 to UTC+12). █ = approximate daytime (6 AM–6 PM) · the highlighted column is YOUR current UTC offset right now.

🌅️ Sunrise / Sunset by City (Today)

City	Timezone	Sunrise	Sunset	Day Length

Calculated using each city's coordinates and today's date (NOAA solar position formula, approximate ±1–2 minutes). Times shown in each city's local time.

What is Timezone Converter?

A timezone converter translates a specific date and time from one timezone to one or more others. The world uses 100+ distinct timezones defined by offsets from UTC (Coordinated Universal Time). India Standard Time is UTC+5:30, US Eastern Standard Time is UTC-5, Japan Standard Time is UTC+9, and so on.

This tool uses your browser's built-in Intl.DateTimeFormat API with the full IANA timezone database, which includes complete Daylight Saving Time rules for all regions that observe DST. Conversions are automatically accurate regardless of time of year. You can select multiple target timezones simultaneously using the searchable checkbox dropdown, making it easy to schedule international meetings or verify deadlines across regions.

No data is sent to any server. All conversion happens locally in your browser using native JavaScript APIs that are present in every modern browser.

How to Use It?

Pick a date and time with the datetime picker or click ⏰ Current Time to use the current moment. Your local timezone is pre-selected in the From field. Click Tap to select timezones, search by timezone name or city, and check your target zones. Click 🕐 Convert Now to see results. Each card shows converted time, full date, UTC offset, and timezone abbreviation.

💡 Real-World Example

Example: A project manager in Mumbai needs to schedule a call with developers in New York and London. Entering 7:00 PM IST and selecting both target timezones shows it will be 9:30 AM in New York and 2:30 PM in London — comfortably within working hours for everyone.

🌍 GMT vs UTC — What's Actually the Difference?

UTC (Coordinated Universal Time) is the modern scientific time standard, defined by atomic clocks, and never changes for Daylight Saving. GMT (Greenwich Mean Time) was the historical standard based on the Earth's rotation relative to the prime meridian at Greenwich, London.

	UTC	GMT
Basis	Atomic clocks (scientific standard)	Earth's rotation (historical, astronomical)
Changes with DST?	❌ Never	❌ GMT itself never changes — but the UK switches to BST (GMT+1) in summer, so "London time" ≠ GMT in summer
Numeric value right now	Always UTC+0	Effectively UTC+0 in winter; the UK observes BST (UTC+1) in summer
Used for	Aviation, computing, international standards, IANA timezone database baseline	Casual reference to "UK time" or historical/legal contexts

In practice: For 99% of everyday and technical purposes, UTC and GMT are numerically IDENTICAL (UTC+0). The distinction matters mainly when referring to UK LOCAL time in summer (BST = UTC+1), vs the fixed UTC+0 standard. This tool's "GMT" quick-conversion chips use Europe/London, which correctly shows GMT in winter and BST in summer — matching how "UK time" is used in real life.

⏱ DST (Daylight Saving Time) Explained

Daylight Saving Time is the practice of moving clocks forward by 1 hour during summer months to make better use of daylight in the evening, then back in autumn. Not all countries observe it.

Why it exists

Originally promoted to save energy by aligning waking hours with daylight. Evidence on actual energy savings is mixed, but the practice persists in ~70 countries.

"Spring forward, fall back"

Clocks move FORWARD (lose 1 hour) in spring when DST begins, and BACKWARD (gain 1 hour) in autumn when DST ends.

Who observes it

USA/Canada (most states/provinces), UK & EU, and others. India, China, Japan, and most of the Middle East and equatorial countries do NOT observe DST — their daylight hours don't vary enough seasonally to justify it.

Why dates differ by country

The US/Canada switch on different dates than the EU/UK — for a few weeks each spring/autumn, the time difference between (say) New York and London can be 4 hours instead of the "usual" 5, because only one side has changed clocks yet.

This tool handles DST automatically — the World Clock badges above show "DST Active" or "DST: Standard Time" for any city currently observing Daylight Saving, computed live using the IANA timezone database via your browser's Intl API. The Quick Conversions and Time Difference Calculator also account for DST automatically for the CURRENT date.

🕒 A Brief History of Timezones

Before the railways, every town kept its own "local solar time" based on when the sun was directly overhead — meaning clocks in neighbouring cities could differ by minutes. This became impractical once trains allowed travel fast enough that schedules needed standardisation.

1840s–1850s: Railway Time

British railways adopted GMT for all timetables, gradually pulling local town clocks into alignment with London time.

1884: International Meridian Conference

Representatives from 25 nations met in Washington D.C. and established Greenwich, England as the Prime Meridian (0° longitude) — the reference point from which all 24 standard time zones are offset.

1916 onwards: Daylight Saving adopted

Germany was among the first to introduce DST during WWI to conserve fuel; many countries followed in subsequent decades, though adoption has never been universal.

1972: UTC introduced

Coordinated Universal Time (UTC) was adopted as the new scientific standard, based on atomic clocks with periodic "leap seconds" added to stay aligned with Earth's rotation — gradually superseding GMT as the technical reference.

Today: IANA Time Zone Database

Maintained by volunteers and used by virtually all computers/phones, the "tz database" tracks every historical and current timezone rule worldwide — including DST transitions, government-mandated changes, and even historical one-off shifts. This tool relies on your browser's built-in copy of this database via the Intl API.

📜 Major Timezone Comparison Reference

Quick reference for the most commonly compared timezone pairs. Offsets shown are for standard time; many US/EU zones shift by ±1 hour during their respective DST periods (see DST section above). Use the World Clock and Time Difference Calculator above for LIVE, DST-aware values.

Comparison	Standard Offset Difference	Notes
IST vs UTC	IST = UTC +5:30	India does not observe DST — this offset is constant year-round
IST vs GMT	IST = GMT +5:30 (winter) / +4:30 (UK summer/BST)	Gap shrinks by 1h when UK is on BST
IST vs EST	IST = EST +10:30 (standard) / +9:30 (US on EDT)	US Eastern observes DST (EST↔EDT)
IST vs PST	IST = PST +13:30 (standard) / +12:30 (US on PDT)	US Pacific observes DST (PST↔PDT)
IST vs CST	IST = CST +11:30 (standard) / +10:30 (US on CDT)	US Central observes DST (CST↔CDT)
IST vs MST	IST = MST +12:30 (standard) / +11:30 (US on MDT)	US Mountain observes DST (MST↔MDT) — except Arizona
UTC vs EST	UTC = EST +5 (standard) / +4 (EDT)	"EST" colloquially also used loosely for EDT in summer
UTC vs PST	UTC = PST +8 (standard) / +7 (PDT)	California, Washington, Oregon, etc.
UTC vs GMT	Always 0 (identical)	UTC and GMT are numerically the same — see section above
UTC vs IST	UTC = IST −5:30	No DST adjustment needed for India
GMT vs EST	GMT = EST +5 (winter) / +4 (when both on DST/BST)	Gap changes during transition weeks when only one side has switched DST
GMT vs PST	GMT = PST +8 (winter) / +7 (when both on DST/BST)	Same transition-week caveat as above

📊 Understanding Your Results

Source card

Shows your input time exactly as entered, formatted with the source timezone's abbreviation (e.g. IST, EST) and UTC offset for confirmation.

Timezone abbreviation

e.g. "EST" vs "EDT" — the letter changes automatically based on whether Daylight Saving Time is active for that date, which is why the SAME city can show two different abbreviations depending on the month.

UTC Offset

Shown as +HH:MM or -HH:MM from UTC. This value can differ for the same timezone depending on the date (DST vs standard time) — the tool calculates this automatically for your chosen date.

Date shown per result

Crucially, the DATE can differ between timezones — e.g. 11 PM in Tokyo on Monday is still Monday morning in New York. Always check the date, not just the time.

⚠️ Common Errors & What They Mean

❌ "Please select at least one target timezone"

You clicked Convert without choosing any destination timezones in the dropdown. Open the dropdown, search, and check at least one box.

⚠️ Time is off by exactly 1 hour from what I expected

This is almost always a Daylight Saving Time mismatch — either the source or target region recently changed clocks. The tool uses the IANA database which is always current, so double-check which date you selected.

📅 The converted date is "tomorrow" or "yesterday" unexpectedly

This is correct behaviour when converting across the International Date Line or large offsets — e.g. 11 PM Sunday in Auckland (UTC+13) is still Sunday afternoon in Los Angeles (UTC-8), a full day's difference.

💡 Advanced Tips

📅

Always select the actual meeting date

DST rules differ by date — converting "3 PM today" vs "3 PM in 6 months" for the same two cities can produce different offsets if one region's DST schedule differs.

🕒

Use Current Time for quick checks

Click "Current Time" then select your target timezones to instantly see what time it is RIGHT NOW around the world — useful before calling international contacts.

🌐

Half-hour & 45-min zones

India (UTC+5:30), Nepal (UTC+5:45), and Newfoundland (UTC-3:30) use non-whole-hour offsets — this tool handles these correctly, unlike simple "add N hours" mental math.

✅

Sanity-check business hours

After converting, glance at the date AND time together — a meeting that looks fine time-wise might fall on a weekend in the other timezone.

📜 Common Timezone Offsets Reference

Region	Standard Offset	DST Offset
India (IST)	UTC+5:30	No DST observed
US Eastern	UTC-5 (EST)	UTC-4 (EDT)
UK (London)	UTC+0 (GMT)	UTC+1 (BST)
Japan (JST)	UTC+9	No DST observed
Australia (Sydney)	UTC+10 (AEST)	UTC+11 (AEDT)

FAQ

What is UTC? +

UTC (Coordinated Universal Time) is the primary time standard. All other timezones are expressed as positive or negative offsets from UTC. It is maintained by atomic clocks and does not observe Daylight Saving Time.

✍️ Author: ToolsNovaHub Editorial Team • ✅ Reviewed by: ToolsNovaHub Security & Network Team • 📅 Last Updated: 12 June 2026

What is Daylight Saving Time? +

DST advances clocks by 1 hour during summer months in ~70 countries to extend evening daylight. This tool accounts for DST automatically, so conversions are correct year-round.

Why does India use UTC+5:30? +

India chose a single national timezone offset of UTC+5:30 to roughly centre it geographically across the subcontinent. Several countries use non-whole-hour offsets: Nepal (+5:45), Iran (+3:30), Afghanistan (+4:30).

How do I schedule an international meeting? +

Enter the meeting time in your timezone, select all participant timezones in Convert To, then check if the converted times fall within business hours for each participant.

Does it work offline? +

Yes, once the page has loaded. All conversion uses browser-native APIs and the local IANA database. No internet connection is needed for conversions after initial page load.