How it works
Every modern browser carries a copy of the international time-zone database, which records each region's offset from UTC and its daylight saving history. The converter asks your browser what offset applies in the first zone at the date and time you entered, turns that into a single moment, then asks what the clock reads at that moment in the second zone. Nothing is downloaded and nothing you enter leaves the page. Because the rules come from your browser, keep it up to date: if a country changes its daylight saving rules, browsers learn about it through updates.
New Zealand's two offsets
According to the government's daylight saving page, clocks in New Zealand go forward an hour at 2am on the last Sunday in September and back at 3am on the first Sunday in April. The next change dates it lists are 27 September 2026 (forward) and 4 April 2027 (back). That means the gap to other places changes during the year, and it changes twice when the other place has its own daylight saving on different dates.
- 9am on 15 November 2026 in Auckland (UTC+13) is Sat, 14 Nov 2026, 8:00 pm in London and Sun, 15 Nov 2026, 7:00 am in Sydney.
- 9am on 15 June 2026 in Auckland (UTC+12) is Sun, 14 Jun 2026, 10:00 pm in London and Mon, 15 Jun 2026, 7:00 am in Sydney.
These examples are worked out with the same code the converter uses, by your build machine's copy of the time-zone data.
The nights the clocks change
When daylight saving starts, the hour from 2am to 3am doesn't happen, so a time like 2:30am that night doesn't exist. The converter tells you and moves forward to a real time. When daylight saving ends, the hour before 3am happens twice, so 2:30am that night is ambiguous; the converter uses the first one and says so. If you're scheduling something at those hours, pick a different time.
Mistakes to avoid
- Assuming a fixed difference. "Sydney is two hours behind" is only true for part of the year.
- Forgetting the date line. Morning in New Zealand is often the previous day in the Americas. Read the date in the result, not just the time.
- Using abbreviations. Short names like CST or IST mean different things in different countries. Pick the place by city name instead.
- The Chatham Islands are 45 minutes ahead of mainland New Zealand; choose Pacific/Chatham for them.
Only the two zones you pick are kept in the page address after the # sign, never the time you type. To count down to an event in any zone, use the countdown timer.
Questions people ask
When does daylight saving start and end in New Zealand?
It starts at 2am on the last Sunday in September and ends at 3am on the first Sunday in April, according to the New Zealand Government's daylight saving page.
Why does the time difference to Australia change during the year?
New Zealand and Australia change their clocks on different dates, and not every Australian state changes at all. In the time-zone data, Sydney is UTC+11 in January and UTC+10 in July, while Brisbane is UTC+10 in January and UTC+10 in July. The converter applies each place's own rules for the date you choose.
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