GMT vs HST time zone comparison

How GMT and HST compare

Greenwich Mean Time (GMT) sits at UTC+00:00 today, while Hawaii Standard Time (HST) is at UTC-10:00. The current gap is 10 hours, with GMT ahead of HST. In practical terms, if your morning starts at 9 AM in United Kingdom (winter), West Africa, Iceland, your counterpart in Honolulu is seeing 23:00 on their own watch at that exact moment.

GMT is the working clock for United Kingdom (winter), West Africa, Iceland. GMT and UTC agree to the second in practice. The UK uses GMT in winter and BST in summer. HST covers Honolulu. If your team is split between these two regions, the table above is the quickest way to spot the daily overlap window without doing the offset arithmetic in your head.

Neither GMT nor HST observes daylight saving in the modern era, which is unusual and convenient: the gap between the two zones stays the same in January and in July. You can quote the offset once and forget about it.

Common scheduling traps are easy to avoid here. Pick a wall-clock time on one side, read the matching wall-clock on the other from the table, and write both into the calendar invite, never just the difference. If the meeting falls in the week of a DST changeover and one of these zones shifts, the absolute clock will drift by an hour from what the recipient expects. The table is computed for today's date, so for a future meeting open the converter linked above and pick the exact date.

One last note for asynchronous teams: business-hour overlap is the wrong metric for handoff workflows. If you operate on a follow-the-sun model, you actually want zero overlap, with one team logging off as the other starts. GMT and HST differ by 10 hours, which gives you partial coverage. Add a zone in between if you want full 24-hour rotation.