UTC vs GMT vs EST: Practical Time Zone Conversion
UTC, GMT, and the major US time zones (EST, CST, MST, PST) — how to convert across them, what's the same, what isn't.
UTC and GMT: same and different
UTC (Coordinated Universal Time) and GMT (Greenwich Mean Time) are usually treated as identical in everyday use, both based on international atomic time. The difference is more about who maintains the standard than about precision. Computer systems prefer UTC; British law prefers GMT.
US time zones
| Zone | Abbr | UTC offset (winter) | UTC offset (summer) |
|---|---|---|---|
| Eastern | EST/EDT | -05:00 | -04:00 |
| Central | CST/CDT | -06:00 | -05:00 |
| Mountain | MST/MDT | -07:00 | -06:00 |
| Pacific | PST/PDT | -08:00 | -07:00 |
DST caveat
‘EST’ in strict usage is the fixed -05:00 offset. The summer -04:00 is EDT, not EST. Don’t conflate EST with ET.
Tool
Epoch to DateTime displays across 6 timezones in your browser.
Note
Timezone abbreviations are heavily overloaded (EST has at least 4 distinct meanings). Use IANA names (America/New_York) to avoid ambiguity.
使い方
Open the tool
Open the relevant tool linked below in your browser. The page handles everything client-side.
よくある質問
Does this upload my file?
No. All ToolConvoy tools process files in your browser; nothing is uploaded to a server.