HST to UTC Time Converter

Common Times Converted

HST on the left, UTC on the right.

HST to UTC: Full 24-Hour Conversion Table

Shaded rows are working hours; the darker shade marks the hours when both zones are at work.

What HST and UTC Actually Are

HST — Hawaii Standard Time

Honolulu and the rest of Hawaii. Standing at UTC-10:00 as written, and the region does not change its clocks, so that offset holds all year. Hawaii does not observe daylight saving, so this offset holds all year.

Hawaii dropped daylight saving in 1967 and never resumed it. Being close to the equator, its daylight barely varies across the year, so there is little to gain.

UTC — Coordinated Universal Time

The global reference standard. Aviation, computing and science run on it. Standing at UTC as written, and the region does not change its clocks, so that offset holds all year.

UTC is not a place. It is a computed standard, kept within a second of mean solar time at Greenwich by atomic clocks, and it is the reference every other zone is defined against.

What This Means in Practice

The date changes mid-working-day

For 3 of the eight hours in a normal HST working day, the equivalent UTC time falls on a different calendar date. Anything scheduled in that stretch needs the date checked as well as the time, or a Tuesday call quietly becomes a Wednesday one at the other end.

A gap you can rely on

Neither region changes its clocks, so this difference holds every day of the year. A recurring meeting booked once stays correct — worth knowing, because most cross-border pairs cannot say that.

Nearly opposite sides of the clock

At 10 hours apart, one side's morning is the other side's night. Handing work over at the end of a shift usually beats trying to get both parties in the same call.

Major Cities in Each Zone

Cities on HST