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Time Zone & World Clock Converter
Check current local times, calculate exact time differences between countries, and compare world clocks.
🇻🇳 Hanoi is 11 hours behind 🇺🇸 New York
(Previous Day)Vietnam (UTC/GMT+7) vs United States (UTC/GMT-4)
Hanoi
Vietnam
Wed, Sep 16, 2026
New York
United States
Tue, Sep 15, 2026
How It Works & Methodology
A time zone is a geographical region where the same standard time is enforced for legal, commercial, and social purposes. Earth is divided into 24 standard time zones based on the 360-degree rotation of the planet (approx. 15° of longitude per 1-hour interval).
Coordinated Universal Time (UTC) is the primary time standard by which the world regulates clocks and time. Local times are expressed as positive or negative offsets from UTC (e.g., UTC+7 for Vietnam and Thailand, UTC-5 for US Eastern Standard Time).
Daylight Saving Time (DST) Explained
Daylight Saving Time (DST) is the practice of advancing clocks (typically by one hour) during warmer months so that darkness falls at a later clock time. Clocks are adjusted forward ("spring forward") in spring and set back ("fall back") to standard time in autumn.
Because different countries (and even different regions within a single country) begin and end DST on different dates—or choose not to observe DST at all—time differences between two locations can shift by an hour throughout the year.
Non-Standard & Fractional Time Zones
While most time zones differ from UTC by whole hours, several countries utilize 30-minute or 45-minute fractional offsets to better align solar noon with clock time. Notable examples include India and Sri Lanka (UTC+5:30), Iran (UTC+3:30), Afghanistan (UTC+4:30), Nepal (UTC+5:45), Myanmar (UTC+6:30), and Central Australia (UTC+9:30).
Frequently Asked Questions
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