HST vs JST time zone comparison

How HST and JST compare

Hawaii Standard Time (HST) sits at UTC-10:00 today, while Japan Standard Time (JST) is at UTC+09:00. The current gap is 19 hours, with HST behind JST. In practical terms, if your morning starts at 9 AM in Honolulu, your counterpart in Tokyo is seeing 04:00 on their own watch at that exact moment.

HST is the working clock for Honolulu. JST covers Tokyo, Osaka and Yokohama. 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 HST nor JST 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. HST and JST differ by 19 hours, which gives you partial coverage. Add a zone in between if you want full 24-hour rotation.