Convert date to GMT and UTC

Could you give me a hand, I have the following confusion: If I have the date: 2023-07-25 18:00:00 in GMT-4, what would be the corresponding date in GMT and UTC?

I don't know if I'm confused but GMT and UTC are not the same, does that mean that I add 4 hours to the date?

Since the original time is 4 hours behind UTC, then yes - you would add four hours to get the UTC time.

In other words, using ISO 8601 / RFC 3339 standard notation: 2023-07-25T18:00:00-04:00 is equivalent to 2023-07-25T22:00:00Z.

With regard to GMT and UTC - they are logically the same in modern usage - in that the current GMT time and current UTC time have the same values. When people say that GMT and UTC are not they same, they mean that that they refer to different concepts:

• UTC is Coordinated Universal Time. It is the clock that the world synchronizes all other clocks to, and provides the baseline that time zone offsets and DST rules are applied to become local time.

• GMT is Greenwich Mean Time. In modern usage, it is simply the time in Greenwich, England, UK without regard to daylight saving time (i.e., without British Summer Time). In the past, before the formal definition of UTC, it was also the basis for time synchronization - but that role has since been supplanted by UTC.

Another way to think about it is that UTC has a technical definition, whereas GMT has a legislative definition that only applies in the United Kingdom.