Time Zone Converter

What is Time Zone Converter?

Free time zone converter. Convert time between any two world time zones instantly. Supports IST, UTC, US, UK, Australia and 100+ time zones. Date and time tools that support Indian Standard Time (IST) and the Indian calendar. TekPulse's Time Zone Converter is completely free — no signup, no ads in results, and no data stored on our servers.

How to Use Time Zone Converter Online

1. Select your source time zone (e.g. IST — Asia/Kolkata)
2. Enter the time and date you want to convert
3. Select the target time zone (e.g. EST — America/New_York)
4. View the converted time and the UTC offset difference between both zones
5. Add multiple time zones to compare an event time across several cities simultaneously

Time Zone Converter Formula & Calculation

Rather than hardcoding fixed UTC offsets (e.g. "IST = UTC+5:30"), this tool uses the browser's built-in Intl.DateTimeFormat API with the IANA time zone identifiers (like Asia/Kolkata or America/New_York). The browser's internal time zone database already encodes each region's current offset rules, including daylight saving time transitions, so the same conversion logic automatically gives correct results whether it's summer or winter in a DST-observing region like New York or London.

Example: Converting 10:00 AM IST to New York time gives a different UTC offset depending on whether US daylight saving is in effect (EDT, UTC−4) or not (EST, UTC−5) — the tool reflects whichever is actually in force on the date you select, rather than assuming a single fixed offset year-round.

Key Factors That Affect Your Result

1. Daylight saving time — Because real IANA zone rules are used, DST start/end dates for each region are handled automatically and correctly reflect the selected date, not just the current date.
2. Database accuracy — The IANA time zone database is maintained by browser vendors and updated regularly to reflect real-world political changes to offsets or DST rules, so conversions stay accurate without the site needing manual updates.
3. India has no DST — IST (Asia/Kolkata) stays at a fixed UTC+5:30 year-round, so conversions involving India are simpler and unaffected by seasonal offset shifts, unlike conversions between two DST-observing regions.

Why Use TekPulse Time Zone Converter?